UF & US Bros favorite cartoons, if they watch any? (i rlly like ChalkZone lol)
Underfell!Sans - He... doesn't really watch a lot. And when he does, it's almost always with Alphys. Which inevitably means he's really only watched anime. Though most of them he didn't really like much at all, at least Deadman Wonderland was entertaining to an extent.
Underfell!Papyrus - Absolutely not. He finds most television shows and movies and whatnot (outside of anything MTT, of course) to be boring and a waste of time. He has better things to do then sit and watch TV.
Underswap!Sans - Blue has no time for watching shows. Sometimes he catches the end of something his brother is watching, or hears about some show or another through Alphys or Undyne, but he doesn't have much time at all to watch for himself.
Underswap!Papyrus - He passively watches shows. There's nothing really that Swapap would peg as his favorite, frankly, but his usual go-to show when he's just watching them by himself is Johnny Bravo.
