You ought to stand up anyway.

Why on earth someone would do something so unsanitary in such a public place is beyond me (said the RN). I mean, really - would YOU want to sit next to someone using a travel urinal and have the aircraft hit turbulence (let alone have them using one at all, turbulence or not)? You also know urine has a distinct odor, correct?

I'm a nurse and don't particularly care to encounter that....while that might not be outside the realm of possibility for me while at work, I do not expect to have that happen in a plane!