loo decisions

just a quick decision we (college students) r faced with everyday: which would you rather get: renal stones or a nasty UT infection?
you c, it is simple, if you need to pee anytime while u're in college, u either gotta hold it in till you get home, which if you're lucky and traffic is good would never take less than an hour, or go into the "loo" there. Ahem.. i need not mention the state the toilets r in, i think we all got the picture.
so, basically, what do you do?