Duh it sounds like your mom trying to be cool, these shows are written by a bunch of 80s and 90s kids that are now adults themselves trying to pander to a new generation of youth. a quarter of the references and jokes are going to go over most kids heads, thus the wacky, spastic, ADD nature of the shows, which is what many kids will often find funny just by the nature of the slapstick. The rest is for the parents that have to watch the show too, because not all of us are just going to sit the kid in front of the TV and then walk away for a few hours. I appreciate that about them.
My cousins love Adventure Time, but watching The Regular Show went over ... weird.
This was the first time my wife and I had seen it, and Mordecai and Rigby had to stop some giant bird thing. Climax of the episode, they call on some power, at which point The Touch begins playing, and they summon up all kinds of 90s paraphernalia like the Power Glove, Air Jordans, NES controllers, a robot that's shaped like the original Power Rangers series Megazord, etc. My wife and I were laughing our asses off, and my 10-year-old cousin looked back at us. "What? What is it? What's so funny?"
"Just a bunch of 90s stuff from when we were kids."
He goes back to staring at the screen, scene continues, laughter continues. He starts freaking out. "I don't UNDERSTAND." Staring at the screen. "I DON'T KNOW WHAT ANY OF THIS IS! WHY IS IT FUNNY?" Which only made us laugh harder and then he stormed out of the room.