Mayonnaise
This is the of his senior year in high school. Unfortunately he still has to share a room with his younger brother who is about 5 or 6.
One night, he decides to bring his girlfriend home for a little fun. They have bunkbeds and the guy notices that his little brother is already asleep on the lower bunk, so he and his gal climb up to the top.
As you might expect things start to heat up. The guy, remembering that he little brother is sleeping below, tells his girlfriend to whisper “lettuce” if she wants it harder and “tomato” if she wants a new position. As they are getting into it, she moans, “Lettuce, tomato, lettuce, tomato, lettuce, lettuce!”
Then the little brother chimes in, “Hey, would you guys quit making sandwiches up there? You’re getting mayonnaise all over my face!”