i remember staying round friends houses (read squats that got tidied up quite well when the landlord came round) and the rule being 'if you've been out, piss in the bath, because everyone knows your just gona piss on the seat' and every morning someone would go in with the hose and sort out all the people that managed to miss the bath
but seriously tho, i say put the frickin seat up, i mean c'mon ladies, you're big girls know, you can put the seat down when you need to go, waddya say?
saying that, most of the time i just forget anyway and leave it down.