Octopus' Toilet Call

Listen here, you knucklehead. This joke is funny because it uses "toilet call" instead of "tropical" to make a pun. It plays on the fact that the octopus lives in the ocean and would like to get back to his natural habitat by going down the toilet. A pun is a joke that exploits the different possible meanings of a word or the fact that there are words that sound alike but have different meanings.