Not sure this is the most annoying, but turned out to be nearly the most embarrassing. Flying back home from Australia on the Qantas A380 in Premium Economy yesterday. The two lavs are between business and PE and are adjoining in the center of the plane. I'd noticed on the flight over in the one bathroom there was a small handle and it was hinged such that you could essentially open the divider between the two lavs.
Well, I was in the other one pretty early into the flight home when as soon as I unzip and start the flow, the person in the adjoining lav starts to open said divider. I gently pushed it closed as soon as it started opening thinking the person doing it would quickly realize that isn't the door to get out. I was wrong.
Repeated attempts, with short breaks in between, while I'm trying to finish peeing without either spilling on the floor or being accused of indecent exposure. I couldn't believe they didn't realize that wasn't the door they wanted. They made one final, forceful attempt (at this point I was rather frustrated) that caused me to utter "STOP" loud enough for them to hear while throwing my shoulder into the divider pretty damn hard to make it clear there was a person on the other side who didn't want to share a space with them.
They relented after that, and by the time I finished, washed my hands, etc, they were gone. I was a little flustered, and it's one of those things that happned so fast, but I'm proud to say no urine was misplaced through this little event and no one got exposed.
