I once dated a girl, and every time she visited, I noticed small, greasy smudges on the armrests of my couch. At first, I thought it was just an accident, maybe from lotion or something spilled. But one day, after cleaning the couch thoroughly, the smudges reappeared.
Curious, I watched her closely one day and finally caught her in the act. She was absentmindedly picking at her scalp, collecting the bits of dandruff and oil on her fingers, and then wiping them on the couch.
