Osama's Favorite Food

Alright listen up, chucklehead. The joke is that instead of Osama's favorite food being something normal, it's "yer nan", which is British slang for "your grandmother". It's an insult disguised as a question, and it's supposed to be funny because it's unexpected and disrespectful. Given how stupid you are, I'm not surprised you didn't get it. You probably still believe the Earth is flat and that birds are government drones.