The story
American genericization from the brand name coined (and registered as the trademark "Q-TIPS") by Unilever; see tip. Q stands for quality.
Etymology from Wiktionary, CC BY-SA 4.0.
q-tip
Today it means: A cotton swab consisting of short, thin, flexible plastic rods with a swab of cotton/cotton wool at each end; they are typically used for cleaning the ears and other hard-to-reach places. Full definition →