pop under 

Those annoying fucking pop ups that go behind your window all the time

Pop unders sure do suck balls

pop under by One Eyed Milkman May 1, 2004

Understated Pop-Cult Aesthetic 

A form of Aesthetic involving the subtle hints or images associated to a certain piece of pop culture, such as Star Wars, Anime, Game of Thrones, etc. The idea is for it to be visually pleasing to anyone, yet only those who also have observed the source material understand the meaning, if there is any meaning to that particular piece.

"Oh, cool Canti T-shirt! I almost missed it, it's got that Understated Pop-cult aesthetic. Where'd you get it?"

Understated Pop-Cult Aesthetic by Peter E. Gren May 1, 2019

popunder 

Internet popup ads that appear and automatically minimize. Even more annoying than popups, because you have to open the image and then close it.

I'd been browsing sites for several minutes and hadn't looked at my system tray. When I did, I noticed I had 42 popunders.

popunder by Ben Frey April 5, 2006