Yellow Submarine

Okay, listen up, smarty pants! You see, the joke asks what's yellow and can't swim. You're probably thinking a rubber ducky or a banana, right? But nope! The answer is a school bus full of children. Why can't it swim? Because it's full of children and probably sank to the bottom of whatever body of water it's in. It's funny because it's unexpected and dark, kind of like your future if you keep asking dumb questions.