We had quite a few of the Travel Johns that my wife would use when camping, and I kept one in the airplane as well. She needed it one time, and it was a bit awkward for her to use, but it did work with no mess.
Years ago, I got into a friend's Bonanza for a short flight for breakfast. There was a woman's ankle-high boot on the floor. He chuckled and put it in the back seat area. He said he was flying back from their place in Florida when he had to urinate, so he used a plastic bag. But it started to "weep" at the seam, so he reached into a clothes basket and pulled out one of his wife's boots to hold the plastic bag. He said he didn't want to take it home because he figured the dog would be following her around sniffing her right foot. He made me promise not to say anything.
About two weeks later, we went out to eat and saw him and his wife. They invited us to join them for dinner. As we sat down, he laughed at me and said, "She knows."
