After a while, the artificial insemination man arrives and knocks on the front door. Amy takes him down to the barn. They walk along the row of cows and when Amy sees the nail, she tells him, "This is the one right here."
The man, assuming he is dealing with an air-head blond, asks, "Tell me lady, 'cause I'm dying to know, how would You know that this is the right cow to be bred?"
"That's simple," she said. "By the nail that's over its stall," she explains very confidently.
Laughing rudely at her, the man says, "And what, pray tell, is the nail for?"'
The blonde turns to walk away and says sweetly over her shoulder, "I guess it's to hang your pants on."