Originally part of a humor
ous sign outside a friend's pool
"We don't swim in your toilet
so please don't pee in our pool."
This phrase has been bastardized into one of the funniest ways of dealing with other people's stupidness. Example: my bed is often mistaken for a table by some of the lower primates (aka roommates) i live with. They'll somehow mistake it for a place for them to sort their laundry or a handy place to put their coat when they get in (it's barely cold enough in Georgia to warrant having a coat in the first place, but that's another rant). When i get in, i point out the fact they're using my bed by saying something like "Matt, i don't swim in your toilet, so please don't use my bed as a table."