A: Reader, I love you. (And you, and you, and you. You all ask the most interesting questions.) I called Cynthia Boxrud, MD, assistant clinical professor at the Geffen School of Medicine at UCLA—she's an ophthalmic plastic and reconstructive surgeon—on the off chance she'd have the answer to your somewhat oddball query, and what do you know, she just happened to have spent about a year researching a paper on the anatomy of the medial aspect of the brow. Which means she's very knowledgeable about sneezing as it relates to eyebrow plucking. The facial nerves include the trigeminal, which has a branch that extends from the brow down into the tip of the nose. Sometimes, when plucking your eyebrows, that nerve is stimulated: Aaachoo!
Bottom line: You may be able to avoid sneezing by pressing your finger anywhere against your eyebrow as you tweeze, which, according to Dr. Boxrud, can short-circuit the wiring of the trigeminal nerve.