So, the title of the chapter is 적당히 해 10덕아. 10덕 when pronounced sounds like 씹덕, which means something along the lines of dweeb. And 씹덕 itself is a slang so no surprise they didn't know, even more so since it was spelled like that. Strange because seems like they got the gist of it when it appears in the chapter, although "maniac" is a very unfitting translation here.