You Must Be Single
A woman is shopping in the local supermarket. She selects some milk, some eggs, a carton of juice, and a package of bacon.
As she unloads her items at the cash register to pay, a man standing behind her in line watches her place the four items on the belt and states with assurance, "You must be single."
The woman looks at the four items on the belt, and seeing nothing unusual about her selection says, "That's right...but how on earth did you know?"
He replies, "Because you're ugly."