You can tell a lot about someone's personality by how he orders coffee. "Decaf please, skim milk, no sugar." That's the kind of a guy who goes through the car wash wearing a seat belt.

The quip treats a coffee order as a miniature self-portrait: a highly customized “decaf, skim, no sugar” signals restraint, risk-aversion, and a preference for control. The punchline—wearing a seat belt in a car wash—exaggerates that cautious temperament into absurdity, using hyperbole to mock excessive prudence. Beneath the joke is a familiar social observation: everyday consumer choices can function as shorthand for personality judgments, even when those judgments are unfair or reductive. The humor depends on recognizing how quickly people stereotype others from small rituals and how “health-conscious” or “rule-following” behaviors can be read as uptight.