Substitute
One day as George is sitting in class the teacher is asking everybody questions about their parents and what they do for a living. Everybody replies with doctor, engineer, architect, etc. When it’s Geore’s turn, he tells the teacher that his mom works as a substitute. The teacher asks what kind of substitute and George says, “I don’t know… she just wears high heels and a very short, tight skirt and walks around the street at night.”
The teacher giggles. She says that George is wrong and that it’s not called a substitute, it’s called a prostitute.
George says, “No, my aunt is the prostitute, and when she is sick, my mom substitutes for her.”