Two whales are in a bar...
Two whales are in a bar. One turns to the other and says "OOOOAAAAHHHHOOOOHHHAAOO"
The other whale turns to him and says, "Go home Steve, you're drunk"
This joke is a bar joke, a talking animal joke, and also a joke that sets up one expectation with its setup, and then delivers another joke than is expected.
The setup makes it seem like the whales are normal whales that cannot talk, however when the punch line occurs, it appears that the initial assumption that the listener made (that this was anti-humor, and that the whales are just ordinary whales) was wrong.
Apparently drunk talking whales sound like normal whales?