That's An Old Joke

Alright listen up, buttercup. This joke is basically two insults flying at each other. First, the friend tries to dunk on someone's mom by saying she's so dumb she'd rather watch a couch than the TV. But then BAM! Our comedian comes back swinging, saying that the joke itself is ancient, implying the friend's mom is old as dirt. It is an insult because people don't like being told their mom is old. Also, you must not know anything if you are still telling that joke!