Funny Dirty Joke

There once was this really poor family. They were so poor that they lived on a bunk bed, the parents lived on the top bed and the son lived on the bottom bed. One night the mom and dad were having sex and so they used code words, for harder they said cheese and for faster they said tomato. The kept screaming cheese, cheese, cheese, tomato, tomato, tomato. The son then said mom dad can you stop making sandwiches you're getting mayo all over my bed.