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Please be specific, who said it and what dirty word he say in what page? Edit: sorry wrong page.
Edited by Bubblepig “What is that? It's The Unknown!”
Ant-Man #1, Stinger talks with Symbol Swearing, and Scott Lang (her father) shouts "Whoa! Language!"
Edited by GrigorII Ultimate Secret Wars
One of the common Not in Front of the Kid variants for this one, the kid themselves getting fussed at. (might be common and divergent enough for a subtrope)
Compare Think of the Censors!, its fourth-wall-breaking sister trope.
One guy says a dirty word, and the other guy reprimands him for it.