# Smoke from your mouth **URL:** \ **Category:** Factual Questions\ **Created:** [April 29, 2007, 8:39am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038 "2007-04-29T08:39:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![DevNull](https://avatars.discourse-cdn.com/v4/letter/d/c89c15/32.png) [@DevNull](https://boards.straightdope.com/u/DevNull)\ **Post date:** [April 29, 2007, 8:39am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/1 "2007-04-29T08:39:06Z")
Bear with me… In highschool, us dunderheads could amuse ourselves by blowing hard against the back of our index finger (which sealed our mouth) really hard for thirty seconds, then proceed to blow a puff of a smoke ring of sorts. We had our theories at the time but now I want to know the real science. For the record, I can’t do it anymore for some reason. Almost all of us could back then. What gives? ---
**Author:** ![DevNull](https://avatars.discourse-cdn.com/v4/letter/d/c89c15/32.png) [@DevNull](https://boards.straightdope.com/u/DevNull)\ **Post date:** [April 29, 2007, 8:43am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/2 "2007-04-29T08:43:25Z")
woot! I just did it! So still… what gives? ---
**Author:** ![Toaster](https://avatars.discourse-cdn.com/v4/letter/t/7bcc69/32.png) [@Toaster](https://boards.straightdope.com/u/Toaster)\ **Post date:** [April 29, 2007, 9:04am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/3 "2007-04-29T09:04:05Z")
Just a guess, and I am not attempting to try this as I am sick and do not want the risk of passing out, but are you sure it is actual particulates, and not an optical effect due to strain, making some sort of halo effect? ---
**Author:** ![Captain\_C](https://avatars.discourse-cdn.com/v4/letter/c/e5b9ba/32.png) [@Captain\_C](https://boards.straightdope.com/u/Captain_C)\ **Post date:** [April 29, 2007, 9:05am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/4 "2007-04-29T09:05:52Z")
Saliva under pressure releasing at once in a ring-like form? I can’t get it to work though, and I’m getting too light headed to keep trying. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [April 29, 2007, 9:39am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/5 "2007-04-29T09:39:05Z")
It’s just water vapour caused by releasing high-pressure, moist air. ---
**Author:** ![Contrapuntal](https://avatars.discourse-cdn.com/v4/letter/c/e274bd/32.png) [@Contrapuntal](https://boards.straightdope.com/u/Contrapuntal)\ **Post date:** [April 29, 2007, 10:20am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/6 "2007-04-29T10:20:39Z")
[QUOTE=jjimm] It’s just water vapour caused by releasing high-pressure, moist air. [/QUOTE] I think he’s got it. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [April 29, 2007, 1:01pm UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/7 "2007-04-29T13:01:17Z")
[QUOTE=Toaster] Just a guess, and I am not attempting to try this as I am sick and do not want the risk of passing out, but are you sure it is actual particulates, and not an optical effect due to strain, making some sort of halo effect? [/QUOTE] No, it is very real. We used to do it too when I was younger. ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [April 29, 2007, 5:02pm UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/8 "2007-04-29T17:02:47Z")
I just did it to test. Yup, water vapor coming out of my mouth. No optical illusion, it’s quite visible to third parties. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [April 30, 2007, 8:47am UTC](https://boards.straightdope.com/t/smoke-from-your-mouth/402038/9 "2007-04-30T08:47:46Z")
Here in Minnesota, we can do that about 6 months out of the year. We don’t even have to blow real hard – just do it in winter.