Back in the old days, I used to fly a very fancy, corporate-equipped, leather-lined Shrike Commander with just four club chairs in the cabin and a full wet bar between them. I was making a personal trip with my girlfriend at the time as my passenger. She had to pee. I was at FL180 with a nice tailwind and had no intention of giving it all up so she could use an airport restroom, so I told her to pee in the bar’s ice bucket, which she did.
Forever after, it amused me to hear my legitimate pax in the back saying, “Another Scotch, Ed, On the rocks?”