So a zookeeper is having trouble with his dolphins; they were behaving very badly. He talked to his friend, another zookeeper who had the same problem, but fixed it. In order to more closely replicate the dolphin's natural home, he put some juvenile seagulls in with the dolphins and they calmed right down. So the zookeeper takes his advice, gets the birds, and heads back to the dolphin exhibit. He decided to take a shortcut across the lion exhibit, since they had just been fed and would be napping. He got through safely, but was immediately arrested.
Transporting young gulls across sedate lions for immoral porpoises.
That joke is not mine; I wish it were because it is beautiful. But I read it online about a decade ago and it really struck me as a piece of art.