Whole Lotta Shakin'

Last 3 days this old guy's been coming in, after betting on the ponies, (from which conclude since he bought all the horse racing books in the store, and had a racing form magazine and pays in cash). He got his walkman blasting classic rock, which seems later than his era, and his hips are a-shakin', enough so that seemed like he was either having a fit, trying to catch his balance or rockin' out. Since he never fell, and seemed cognizant, guess it was the 3rd. He made a total mess of every shelf he looked at, leaving piles everywhere and randomly reshelving everything, really getting annoying, until he drops 2 bills on some books, each day, then his behaviour becomes merely eccentric...