Phonetics-Based Humor

I just heard this joke and got a kick out of the humor that results when playing with the sounds in a well-known noun phrase.

What do you get when you feed a mallard to a cat?

A duck-filled, fatty-puss.

By substituting a labiodental fricative, /f/, for the first two bilabial stops, /b/ and /p/, and by deleting the second alveolar liquid, /l/, a duck-billed platypus becomes a duck-filled, fatty-puss.