What happens when you hold your breath and try to exhale really hard? If you do it for a while it gives you a headache and makes your face turn red, but why? Does the throat-pressure block the blood from leaving your head? What other effects could it have?
Note: I do NOT recomend trying this as it is most likely a Bad Thing.
Look in the Yellow Pages under “Psychiatry”.
I think you can blow out your eardrums, which, fortunately, I have never done. However, I have been assured it is quite painful and messy.
Ever see Scanners?
Don’t do it. It’s called the Valsalva maneuver. You are mucking about with the vagus-carotid mechanism that controls heart rate in relation to blood pressure, and it will make you faint, or worse.
Do that and also stand against a wall. Have someone push on your chest while you do it. You won’t explode, but you’ll pass out and maybe crack your head on the ground. The best I can think of.
Teebone
I just tried it and my head exploded.
Seriously, I have done this before, and it “popped” my ears (like the popping associated with changes in air pressure on airplanes). I imagine if you do it hard enough, it could damage your eardrums.
We used to do this in Jr. High all the time. I have no idea why, I guess it’s just one of those things that Jr. High kids just have to do.
My face would turn a blue/purple color and my eyes would turn red and I would feel really naseous afterwards. It seemed like the more often I did it the longer the side affects lasted so I quit doing it.
I imagine I would probably vomit if I did it now.
Pilots do it when in a high G force environment to help keep blood up in the brain.
I’ve found that if I hold my breath that way while wearing my aluminum foil hat it keeps the aliens out of my head.
I did this in 3rd grade. Made my face all purple just before passing out and cracking my head on the floor. It pushes blood up into your head, reducing the proper flow, and eventually there isn’t enough O[sub]2[/sub] to keep you conscious.