Just don't be one of those people who raises holy hell when a peon sneaks into a forward lav, yet you think nothing of going in the opposite direction if the need should arise. People should certainly try and stick with the lav in their cabin, but no one should be forced to soil oneself or suffer from kidney damage due to an imaginary line. This is especially relevant as many airlines continue to eliminate lav's in Y on wide-body aircraft to squeeze a few more rows of torture chambers on-board.