I think this is about how this joke goes, so bear with me, here. *Ahem*.

There's a schoolbus driver doing his daily routine, and one of the kids he picks up is one of "those" bright little stars;

Side note - Come to think of it, a lot like Twilight.
Anyway, one of those.

She's apparently doing an extra credit assignment, or something. One about hybrid animals. And, of course, she has the habit of thinking aloud. So occasionally she's saying things like "Hmm... If my mother was a donkey and my father was a zebra, I'd be a Zonkey." or "If my mother was a tigres and my father was a lion, I'd be a liger..."

After a while of this, the driver's had enough of this and decides he'd try to give her... something else to think about.

"So if your mother was an idiot and your father was a drunkard, what would that make you?"

She takes that as a serious question. Indeed, for a moment, she is stumped. She thinks for a moment and says "... I dunno, Maybe... a... bus driver?"

The guy winces, but gives a bark of laughter, says "I walked into that; Fair enough." and goes back to concentrating on driving.

7736520

and goes back to concentrating on driving.

But then he realizes that he already crashed the bus and everyone on it is now dead.

7736520 I mean I think it's funny.

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I'm personally fond of jokes that are good and clean. As far as I'm concerned, if you need to make a clean joke into a dirty one to make it amusing, it wasn't worth telling.