I grabbed this one from one of the crabbing board:
A recreational fisherman got stop by a DNR cop with a cooler full of fish (DNR = department of natural resource). The DNR cop asked the fisherman if he has the license to fish. The fisherman told the DNR cop that they are his pets and he would take them out every day for a swim.
The DNR cop would not believe his story and asked him to demonstrate. The fisherman then pour all of the fish to the water and stood there. The DNR cop getting impatient and told the fisherman to call his fish back. The fisherman scratched his bald head and said "what fish?"