Because it messes with their hops
You poke 'em on.
Hop in
Freud rice.
Not enough cement EDIT: Okay thanks for pointing out that I messed up the wording but the joke is supposed to be the funny part
A magician makes rabbits appear in hats, while a psychologist makes habits appear in rats.
A: Because from a distance they looked like hares.
Because you can't drink and derive
You can spill your beer on a fiddle.