The Dairy Maid

When you're stroking a person's dick (they're on all fours), and right as they're about to cum, you yank on their balls like you'd yank on a cow's teat, and they "mooo!" in pain.

I gave a guy the funniest blue balls the other night, both figuratively and literaly; hit 'im with the dairy maid.
The amount of therapy he'll need after that night is gonna be expensive, but his reaction was priceless!