The epileptic goldfish
An owner of a goldfish went to the vet saying he believed his goldfish was epileptic.
The vet picked up the bowl, turned it one way, then the other and he said to the owner, "I think your goldfish is fine."
The owner then grabbed the goldfish and laid it on the vets desk, and it started flipping and flopping around everywhere.
"See??" said the owner. "My goldfish IS epileptic."