I usually got so paranoid about dropping a deuce on board that I would OD on vitamin I & turn my eyes brown for a few days.
In the grand scheme, it probably wouldn't have mattered, those old girls are permanently imbued with the stench of 50+ years of sweat, farts, boogers, vomit, anger, frustration, and despair, with an underlying hint of cigarette smoke & anti-commie sentiment around the sextant port.
It's a beautiful thing.