From Good Clean Funnies
Dewey goes to a pet shop, and there he sees a parrot with a red string tied to its left leg and a green string tied to its right leg.
He asks the owner the significance of the strings.
"Well, this is a highly trained parrot. If you pull the red string, he speaks French; if you pull the green string, he speaks German," replies the shopkeeper.
"And what happens if I pull both strings at the same time?" asks Dewey.
"I fall off my perch!" squawks the parrot.