I have two coworkers who sit on either side of my main cubicle. One is doing a project with a lot of phone calls. The other blows her nose louder than I ever thought possible, and gets upset when I ask her to do that in the bathroom.
I refer to the two of them openly to my other coworker as Megaphone and Matterhorn.
I walked in this morning, sat at my desk, and, without thinking, greeted one of them (whom I could hear coming) with "good morning, Megaphone" (instead of "good morning, [insert name here]").
I promptly grabbed all 7 binders for my qualifying exams and hauled down to the student center to hide/avoid noise/avoid being asked why I called her Megaphone.