Theres a blonde, a brunette and a red head. They're all going to a castle. But this castle is so magical, it knows when people lie, and if they do, they got shot into the air by a cannonball.

So the brunette walks up and says "I think I'm sexy!"
The castle lets her in.

The red head walks up and says "I think I'm beautiful!"
The castle lets her in.

The blonde walks up and says "I think..." She gets cut off and shot into the air