"Knock, knock."
"Orphan: Who's there?"
"Not your parents."
"Knock, knock."
"Orphan: Who's there?"
"Not your parents."
Listen up, nimrod! This joke is funny because orphans don't have parents. When the orphan asks "Who's there?" the answer is "Not your parents," which is a brutal reminder that they're parentless. It's funny 'cause it's sad, and you probably laugh at squirrels getting hit by cars too, you sicko.