Quote from Harry in Superstitious Dick
Woman: Excuse me. How do you tell the difference between a 1/2 inch dowel and a 3/8 dowel? Harry: You know, I've been getting this a lot lately. There's a standard rule of thumb. Okay, now, the 3/8 dowel fits perfectly in my ear. Whereas the 1/2 inch dowel does not. Woman: Okay, thanks. [walks away without the dowels]