Because there used to be 2 of them, but it's offensive to joke about that now.
If you take one, he'll drink all of your beer, If you take 2 neither will drink a drop
Her name was Cindy she had a husband and 2 children
H Edit: I don't like explaining jokes but since the first guy didn't get I might as well: When pronounced in a French accent it sounds like ash.
9 polar bears (joke on a mug at work. lame, ik)