Because it would fall over if it lifted the other one.
or
Shamboo!
Frankenstein: Witch can you make me a lemonade?
Witch: Poof you are a lemonade!
or
Because each player raises a racquet.
or
They're both plastic and little boys turn them on.
or
Stinker Bell.
or
I better not tell you, it might spread.
or