Yes I've wondered about this. The witless filth I mean. I used to get requests, in pubs, for songs like "Running Bare" oops I mean Running Bear" so they could sing "without your pants on" at the end of EVERY line. Tiresome! so tiresome! I once was singing to a bunch of very little kids in a school and they wanted "If I were a Rich Man" I couldn't fathom it. I asked them to sing it for me and they were delighted. They came to "...... biddy biddy bum" and we all fell about laughing. For the benefit of Americans BUM is a very rude word in Australia if you are a little kid. Or was.
So I think it all starts early.