Some kid with parents: "Knock, knock."
Orphan: "Who's there?"
Some kid with parents: "Not your parents."
Alright, listen up, you dummy. This joke is funny 'cause the first kid is like, "Knock, knock," right? And the orphan answers, but then the first kid roasts him by saying, "Not your parents." It's funny 'cause orphans don't have parents, you walnut. I bet you still think milk comes from the store.