Little Johnny sat playing in the garden. When his mother came out
to collect him, she saw that he was slowly eating a worm.  She turned
pale. "No, Johnny!  Stop!  That's horrible!  You can't eat worms!"

Trying to convince him further, "Now the mother worm is looking
all over for her nice baby-worm."

No, she isn't," said Johnny.

Why not?"

Because I ate her first!"