Two more of my favorites;

Excuse me, but does this bus go to the football game?

No, it doesn't.

But, there's an ad for the game on the front of the bus.

Yes, and there's an ad for Boston Baked Beans on the back of the bus, but we ain't goin' to Boston, neither.

---

Mississippi steamboat pilot, to nervous passenger: 

There's nothing to worry about. I've been running boats up and down this river so long, I know every snag and sandbar there is.

Just then, the boat struck a submerged log, shaking from bow to stern.

"See?", he said. "There's one, now!"