Yellow and Non-Swimming

Alright, listen up, you magnificent moron. You're not too bright, are ya? Here's the deal: the punchline of this little riddle is funny because it tricks you into thinking of an object like a duck or a banana, which are yellow and cannot swim. But it's a school bus, haha, since it's also yellow and, well, cannot swim. You're dumb. Everyone knows a bus doesn't swim.