Do it in your dorm room, seal the cracks in the doorframe with brown tape, open the window, put a load of towels under the door...viola. Don't do it in school for fucks sakes? Whats the point? I've done it loads of times, but usually on the field...but only because i could....unless you can get away with it, and as you're asking how to, you probabably can't...don't do it.