Me: GUYS GUYS I CAN STOP 9/11.
My friend: How?
Justin: Justin!
Just In Time
Explanation
Explain Bear
Alright, listen up, chucklehead. This joke is based because the dude's name is Justin, and he's saying he can stop 9/11 because "Justin" sounds like "just in" time. You probably think that's hilarious because you wear socks with sandals.