# Tennis balls and locks **URL:** \ **Category:** Factual Questions\ **Created:** [February 10, 2007, 9:32am UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603 "2007-02-10T09:32:13Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![indierock82](https://avatars.discourse-cdn.com/v4/letter/i/f14d63/32.png) [@indierock82](https://boards.straightdope.com/u/indierock82)\ **Post date:** [February 10, 2007, 9:32am UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/1 "2007-02-10T09:32:13Z")
Is it really possible to unlock a car with an electronic locking mechanism using a tennis ball with a small hole in it? The video I saw claimed that the air pressure that is created while pushing the ball against the lock will force the locking mechanism into unlocking the car. I am, of course, skeptical that it could really be this easy. ---
**Author:** ![TJdude825](https://avatars.discourse-cdn.com/v4/letter/t/dec6dc/32.png) [@TJdude825](https://boards.straightdope.com/u/TJdude825)\ **Post date:** [February 10, 2007, 9:47am UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/2 "2007-02-10T09:47:32Z")
Note that if it’s not true, someone will be gullible enough to try it, and will therefore have to poke a hole in a tennis ball. This causes a small loss of time and property to an unknown number of people, which directly results in the person who came up with this getting a laugh at said people’s expense. The concept is the same as those “forward this email to all your friends, and you will instantly getting a check for $236” emails. It forces you to expose your own gullibility to your friends, who will (the pranksters hope) laugh at you, and then they get a kick out of the whole situation. Unless of course, your friends are equally gullible, in which case the email gets sent all over the internet innumerable times, annoying lots and lots of people. :smack: Even without taking that into account, it sounds extremely unlikely to me. ---
**Author:** ![indierock82](https://avatars.discourse-cdn.com/v4/letter/i/f14d63/32.png) [@indierock82](https://boards.straightdope.com/u/indierock82)\ **Post date:** [February 10, 2007, 11:22am UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/3 "2007-02-10T11:22:45Z")
Yeah, but the thing is that i saw a video on a site where they demonstrated it and it did work. But I’m still skeptical because the car in question was an old car and I think they just used clever video editing to make it look legit. I didn’t know if I could link the video in case it was conceived as promoting of deceit. If the mods say it’s ok, then I’ll link it. ---
**Author:** ![Full\_Metal\_Lotus](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Full\_Metal\_Lotus](https://boards.straightdope.com/u/Full_Metal_Lotus)\ **Post date:** [February 10, 2007, 11:58am UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/4 "2007-02-10T11:58:53Z")
I saw the video too, and the woman demonstrated it was an electronic lock… all it would take is somebody standing off camera with the key fob, unlocking the car while she 'used" the tennis ball… Still I am tempted to try it, even though my inner physicist says “ha ha … you fool!” regards FML ---
**Author:** ![indierock82](https://avatars.discourse-cdn.com/v4/letter/i/f14d63/32.png) [@indierock82](https://boards.straightdope.com/u/indierock82)\ **Post date:** [February 10, 2007, 12:16pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/5 "2007-02-10T12:16:54Z")
Haha, exactly my thinking! But just to be sure, I’m probably going to end up trying it at some point. What’s to lose? 🙂 ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [February 10, 2007, 12:31pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/6 "2007-02-10T12:31:14Z")
[QUOTE=indierock82] Haha, exactly my thinking! But just to be sure, I’m probably going to end up trying it at some point. What’s to lose? 🙂 [/QUOTE] The tennis ball, and the time spent trying it for starters. ---
**Author:** ![indierock82](https://avatars.discourse-cdn.com/v4/letter/i/f14d63/32.png) [@indierock82](https://boards.straightdope.com/u/indierock82)\ **Post date:** [February 10, 2007, 12:34pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/7 "2007-02-10T12:34:08Z")
Burning a hole in a tennis ball = like 1/2 minute (heating up a screw driver and jamming it in the ball) Time spent trying it out = oh I’d say like 1 minute depending on how many tries. So all in all I’m really not losing much of anything. I’ll get back to you guys at some point. ---
**Author:** ![Garfield226](https://avatars.discourse-cdn.com/v4/letter/g/9e8a1a/32.png) [@Garfield226](https://boards.straightdope.com/u/Garfield226)\ **Post date:** [February 10, 2007, 12:37pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/8 "2007-02-10T12:37:53Z")
[QUOTE=indierock82] Time spent trying it out = oh I’d say like 1 minute depending on how many tries. [/QUOTE] Err…if you try it once, and it doesn’t work…you’re going to try AGAIN? ---
**Author:** ![Mince](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@Mince](https://boards.straightdope.com/u/Mince)\ **Post date:** [February 10, 2007, 12:43pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/9 "2007-02-10T12:43:28Z")
[QUOTE=TJdude825] Unless of course, your friends are equally gullible, in which case the email gets sent all over the internet innumerable times, annoying lots and lots of people. :smack: [/QUOTE] Thankfully, this never happens. ---
**Author:** ![Full\_Metal\_Lotus](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Full\_Metal\_Lotus](https://boards.straightdope.com/u/Full_Metal_Lotus)\ **Post date:** [February 10, 2007, 1:36pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/10 "2007-02-10T13:36:02Z")
Yes, it worked, and i can tell you how, honest gentlemans, if you just send me a refund of $500 on the special nigerian tennis ball i am parting with for just $5000, but for you and alls, just $4500! Regards (on a treeadmill) FML ---
**Author:** ![Fridgemagnet](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@Fridgemagnet](https://boards.straightdope.com/u/Fridgemagnet)\ **Post date:** [February 10, 2007, 1:41pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/11 "2007-02-10T13:41:18Z")
This technique works with some of the older Mercedes models that have pneumatically-operated central locking, and a tennis ball cut in half skillfully plungered over the keyhole could pop the doors open. Merc have long since found a workaround for that particular quirk. Also the luxury manufacturer who fitted a crash sensor in the front bumper (fender) to unlock the doors in the event of a collision - they could also be unlocked by giving the car a kick in just the right place. I’m not a car thief, BTW, just someone who gets locked out from time to time, and it’s not difficult to break into my own house or car as I know most of the weaknesses. Worryingly, I’ve never had to explain myself to anyone, not even the time my car ignition key snapped off in the lock and I had to abandon my car on the busy road where it died, fotunately only 100 yards from home and all my tools, and then return with a bunch of stuff to strip down the steering column trim and break the steering lock with a cold-chisel and a big hammer. Even the couple of police cars that passed me weren’t too interested in someone hammering open a steering lock in broad daylight. ---
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [February 10, 2007, 4:27pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/12 "2007-02-10T16:27:15Z")
Here is the video for those interested: [Unlock a Car with a Tennis Ball](http://www.i-am-bored.com/bored_link.cfm?link_id=21882) ---
**Author:** ![indierock82](https://avatars.discourse-cdn.com/v4/letter/i/f14d63/32.png) [@indierock82](https://boards.straightdope.com/u/indierock82)\ **Post date:** [February 10, 2007, 11:28pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/13 "2007-02-10T23:28:40Z")
**Garfield226** Of course you would try it again. What - you fail once and never try something again? Where’s the perseverence?! ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [February 11, 2007, 2:24am UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/14 "2007-02-11T02:24:18Z")
[QUOTE=Fridgemagnet] This technique works with some of the older Mercedes models that have pneumatically-operated central locking, and a tennis ball cut in half skillfully plungered over the keyhole could pop the doors open. Merc have long since found a workaround for that particular quirk. Also the luxury manufacturer who fitted a crash sensor in the front bumper (fender) to unlock the doors in the event of a collision - they could also be unlocked by giving the car a kick in just the right place. [/QUOTE] Could I get a cite or two for these claims? :dubious: In reverse order, many airbag systems unlock the doors when a crash pulse is detected. However, this happens at the same time the airbags deploy. Also on every car I am aware of the airbag system is inoperative when the key is off. So I call bullshit. However if you locked your keys in the car with the engine running, you could ram the front of the car with another car at say 15 mph and the doors would unlock. However I feel confident in saying that the body repairs would far exceed what a locksmith would have charged. As far as the Benz pneumatic locks go, the key rotates in the lock. When the key rotates as I understands it vacuum is then directed or vented to the pneumatic actuators. The pneumatic system is isolated from the inside of the doors. I cannot see how applying air pressure to the door lock will cause the cylinder to rotate. So again I call bullshit. As far as the OP goes, the same problem occurs. How in the name of Henry Ford is the air pressure from the tennis ball going to cause the lock cylinder to turn? Complete and utter bullshit. The technical term for that video is “practical joke” [hijack] So when I got my first car that had a remote unlock I took it over to show to a friend of mine. As we walked up to it, I reached in my pocket and pressed the unlock button on the remote. The lock popped and the lights flashed. “How did you do that”, she asked. “Oh,” I replied, “the car knows me and when I approach, it unlocks itself.” “Really?” “Yeah, watch what happens when I walk away.” At this point I step back and press the lock button, car locks. I step forward, and press the unlock button. I step back and lock it again. “That is amazing” she said. “So now you try it,” I say She steps forward and nothing happens. “How come it did not unlock?” “The car doesn’t know you, let me introduce you” I step forward, unlock the car as I approach and say in a loud commanding voice “Car, this is Joann, she is authorized access.” We both step back and I lock the car. “Go ahead,” I tell her, “try it” She steps forward, and as she crosses the imaginary line I unlock the car. “Wow that is the coolest thing ever!” I did finally come clean, and admit the joke. [/hijack] ---
**Author:** ![anson2995](https://avatars.discourse-cdn.com/v4/letter/a/c77e96/32.png) [@anson2995](https://boards.straightdope.com/u/anson2995)\ **Post date:** [February 11, 2007, 4:26pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/15 "2007-02-11T16:26:42Z")
[QUOTE=indierock82] Haha, exactly my thinking! But just to be sure, I’m probably going to end up trying it at some point. What’s to lose? 🙂 [/QUOTE] You’re going to end up with a dent in your door. ---
**Author:** ![FRDE](https://avatars.discourse-cdn.com/v4/letter/f/e68b1a/32.png) [@FRDE](https://boards.straightdope.com/u/FRDE)\ **Post date:** [February 11, 2007, 4:38pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/16 "2007-02-11T16:38:32Z")
[QUOTE=Fridgemagnet] Worryingly, I’ve never had to explain myself to anyone, not even the time my car ignition key snapped off in the lock and I had to abandon my car on the busy road where it died, fotunately only 100 yards from home and all my tools, and then return with a bunch of stuff to strip down the steering column trim and break the steering lock with a cold-chisel and a big hammer. Even the couple of police cars that passed me weren’t too interested in someone hammering open a steering lock in broad daylight. [/QUOTE] In 1976 I locked myself out of the car - in Hamburg airport car park. The next day I returned with a small toolkit and started working on it. It landed up with me on the bonnet, hacking at the windscreen with a small hammer, blood pouring from my hands, and tears of rage (and pain) pouring from my eyes. I ripped the windscreen out - but it was a close run thing. It was broad daylight and nobody batted an eyelid. ---
**Author:** ![WhyNot](https://avatars.discourse-cdn.com/v4/letter/w/c77e96/32.png) [@WhyNot](https://boards.straightdope.com/u/WhyNot)\ **Post date:** [February 11, 2007, 4:47pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/17 "2007-02-11T16:47:17Z")
[QUOTE=FRDE] It was broad daylight and nobody batted an eyelid. [/QUOTE] I suspect you were unwittingly caught in a [Somebody’s Else’s Problem field](http://en.wikipedia.org/wiki/Somebody_Else's_Problem_field) and were therefore rendered invisible. ---
**Author:** ![Don\_t\_fight\_the\_hypothetical](https://avatars.discourse-cdn.com/v4/letter/d/59ef9b/32.png) [@Don\_t\_fight\_the\_hypothetical](https://boards.straightdope.com/u/Don_t_fight_the_hypothetical)\ **Post date:** [February 11, 2007, 6:14pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/18 "2007-02-11T18:14:14Z")
Why would you carry a tennis ball when a spare key is so much more compact? ---
**Author:** ![Scruloose](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@Scruloose](https://boards.straightdope.com/u/Scruloose)\ **Post date:** [February 11, 2007, 6:25pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/19 "2007-02-11T18:25:09Z")
I read the thread. I agreed with the above posters who suggested that even attempting this trick would be ridiculous. “Besides…” I said to myself, “I don’t have any tennis balls.” Not 20 minutes later, a tennis ball goes flying through the living room, courtesy of my young son who found it in the basement. Fate, I decided. How could I resist? So, count me as ‘one idiot’ who cut a hole in a tennis ball (Penn 4), went outside, in 10F weather, and attempted to open his door with a tennis ball. In broad daylight, no less. And you know what?!? It didn’t work. So for the sake of fighting ignorance, a Penn 4 tennis ball will not open the driver’s side lock of 2005 Chevy Impala in 10F weather. And the neighbors must think I’m nuts. ---
**Author:** ![Chew\_Barker](https://avatars.discourse-cdn.com/v4/letter/c/7bcc69/32.png) [@Chew\_Barker](https://boards.straightdope.com/u/Chew_Barker)\ **Post date:** [February 11, 2007, 6:48pm UTC](https://boards.straightdope.com/t/tennis-balls-and-locks/391603/20 "2007-02-11T18:48:19Z")
**This does work !** When I was about 8 or 9 I watched my dad do this to get into our [Alfa Sud](http://en.wikipedia.org/wiki/Alfa_Romeo_Alfasud). We were on a camping holiday and locked the keys in the car, after trying loads of other methods to get in (such as palms pressed against the window to slowly push it open) some other camper sugested the tennis ball trick. It took a couple of attempts but it did work. 5 or 6 years later my dad performed the tennis ball trick to my scout troup. This time on a [Citroen BX](http://en.wikipedia.org/wiki/Citro%C3%ABn_BX). [Next page](https://boards.straightdope.com/t/tennis-balls-and-locks/391603.md?page=2)