An Extreme Close-Up of something disgusting. If done in an animated series, the close-up is usually drawn in a much more detailed style than the rest of the show.
First recognized in The Ren & Stimpy Show as it was used extensively, but the trope can be considered older than dirt in the sense that looking at something up close is bound to reveal its imperfections. John Kricfalusi, the creator of Ren & Stimpy says he drew the inspiration from Fleischer Popeye cartoons, though it was co-creator Bob Camp who coined the term “gross up.”
