We were on vacation out west in either 1972 or 1974, so I would have been 8 or 10 years old. I'm using the urinal at the end of the hike through Carlesbad Cavern, where they have a large cafeteria and elevators to take you back up to the top of the cave.
Some old guy says to me, "No matter how much you shake or dance, the last few drops go in your pants."