What did the planes say when they were smashing or passing the Twin Towers?
Smash.
(Get it?) 9/11.
Listen up, numbskull. This joke is about 9/11. The punchline is "Smash," which is what happened when the planes hit the Twin Towers. It's funny because it's tragic! And you're laughing. You probably also think the Earth is flat, you absolute cabbage.