Uhh, they should have covered this in school even if your parents neglected to do so, but here you go.
That's punching down.
You imply they're stupid or ignorant. You imply their parents didn't teach them life lessons and you do all that while speaking down to them like you're better than them. They clearly didn't get the joke and instead of elucidating them you go on this tirade about how it's ok to be a jerk if you're making a joke. It's not.
That's neat, no one gives a shit about the shitty joke. People care that they decided to punch down on some random to set up a terrible fuckin joke and instead of being like "hey my bad I could have waited for literally anyone who got the joke to set me up instead" they decided to double down on being a condescending dickhead.
That's how you feel, that isn't however factually sound even by the jerks admission.