How do you get two whales in a car?
Q: How do you get two whales in a car?
A: Start in England and drive west.
This is a pun, and also anti humor, but it is also a deconstruction of a elephant joke. The elephant version is
Q: How do you get four elephants in a car?
A: Two in the front seats, two in the back seats.
If the listener is expecting something along those lines, the answer would be quite unexpected, and therefore funny.
Now, to explain the pun, whales and wales are pronounced (to an american) identically, and so the place and the animal can easily form a pun.