From Douglas Adams Hitchhiker's Guide to the Galaxy series. The best series in the history of ever.
"I didn't say anything, I was about to ask what the silver..."
"Oh, I thought you said 'whop.'"
Watch out for them whops. They like to cause trouble
Such a motion (a whop) if strong enough will usually make the girl's breasts and buttcheeks jiggle if the girl has prominent enough of these features.
The girl on the dance floor is whopping to the music.
That bellydancer must have did at least 100 whops.