You guys have too much free time on your hands. 
That’s not free time on my hands.
–Tim
Was gonna get my kids yo-yo’s for Christmas, but you guys have solved my gift-giving early. And they’re free. Thanks. 
for those that are interested, there is a muscle that runs down next to the spermatic cord and vessels to the testicle. There’s one for each testicle. The muscle is called the cremaster (I guess this is latin for something or other - I should also admit that this is from my knowledge of animal anatomy as a vet though I presume it’s the same for humans) and is the one responsible for pulling the testicles up or letting them down.
Wow, tadpole! Welcome to the Straight Dope! You can always look back in pride and remember that your first post here on the SDMB was about testicles.
thank you! I’d been wondering when I’d get to use that um… interesting tidbit of information…
It works! I can’t really control them, yet, but I can make them go faster. Yes, I’m easily amused. I’ll keep you updated on my progress.
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Not only do the testicles move, but so does the penis. I don’t mean getting an erection, either. If you stare at your penis (assuming it’s non-erect), you’ll see that it expands and contracts, like an inchworm that’s not going anywhere.
I know why my balls are moving, but why my penis?
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Uh-oh. Since this thread seems to have started a new fad in personal, uh, fitness. . .
Move over Thighmaster, make way for the Cremaster-master!!!
I’ve watched mine jump around too. my wife really thinks this is funny, she likes to run her fingernails on my inner thigh and they tend to jump. then she giggles and does it again. women.
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My ex used to find mine funny, too. When we were gonig at it pretty good, she’d hop over to the side, throw the sheet over Mr. Happy and tell me to make him jump. That used to entertain her to no end. TMI?
Sorry about that.
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When I was prepubescent, I used to play lots of games with my penis. My two favorites were “hide the peepee” and “wave the peepee”. The first involved stuffing the penis up inside the body, so there’s almost nothing sticking out. The other involved contracting my muscles so that my penis would jump up and down. I could do it in time with music.
At the tender age of 11, I made the mistake of showing off my skills to my two younger sisters (I never did have any shame). They shrieked with laughter, and ran around the neighborhood telling everybody… I still get reminded of that from time to time.
Each and every one of you guys is guilty of Heresy.
Of course testicles don’t move. Everyone knows that testicles remain fixed and the universe moves around them.
Geez.
Q: How many testicles does it take to change a lightbulb?
A: One Pair. They just hold the lightbulb and the world revolves around them.
Sorry, Manny, I had to. 
I’d try this, but I’d freak out my roommate beyond beleif.
I was waiting for this to load and re-read the OP. Cisco actually says “Have you ever looked intently at your testicles for any amount of time?”.
Sorry, but this strikes me as really funny. Cisco setting around staring INTENTLY at his balls.
:snort:
:giggle:
BWAHAAHAA!!!
Sorry, man, really, no offense meant. Honest.
But the mental image…
Damn, now I forgot what I was going to post.
Still friends?
Oh, yeah:
Q: How do you tell if a girl is ticklish?
A: Give her a couple of test tickles!
Now I’m leaving to stare intently at my balls.
Hey, do we need a special smiley for this?
I could see it coming in handy like when someone is apparently not paying attention or is distracted.
Just don’t name it after me!
I all for the smiley idea. It could be a smiley sitting at 270 degrees with a confused look on it’s face. :testiclestare:
As someone who went through more than four years of infertility treatment, I can TELL you that sperm dies at elevated temperatures. Avoiding hot baths, hot tubs and tighty whities are all recommended by the Doctor. Sorry, no myth. Don't even ask me for a cite, my god- try the AMA.
Cartooniverse, a 38 year old male
Why do they shrink or tighten up right before ejaculation? That’s the only time I’ve noticed that they move, but I’ll definitely have to look into this when I get home and see my husband!