This came as a surprise to me, since it was directed to me by a friend. Time for some Mature Musings!
This one comes from The Amazing World of Gumball, specifically the episode "The Rerun". The context is that the Watterson parents got turned into babies by the effects of the weirdness of the day. When time was reset, there's a brief frame of the parents in their underwear... only with Nicole missing something up top.
It amazes me that this got in on current era Cartoon Network. This is usually the kind of gag you'd see in adult cartoons, and yet it's done in a show for children. This is very good; it shows that things are getting into a position where this kind of gag can happen with females, too, which is all too fine by me.

Reposted from arcroyale