My grandpa was in 9/11. He was the best pilot.
Best 9/11 Pilot
Explanation
Explain Bear
Alright, listen up, you dum-dum. This joke is dark, like your future. The joke implies the grandpa was a pilot on one of the planes that crashed into the Twin Towers on 9/11. It's funny because it's super inappropriate and unexpected. And about you, I bet you still think the Earth is flat, don't you?
Gwen
Sad...