This trope applies to words and names that when uttered cause a negative reaction on the listener's part. It may result from hearing a certain slang term or after a character gives Too Much Information--it might even have a potent psychological effect. Regardless of how it arises, the hapless hearer makes it clear to the speaker that this must not happen again. For instance, for some particularly lazy and/or slobby characters, benign words like "work" and "clean" have been known to cause shivers. This is usually followed by some variation of "don't say that word around me!"