leaving a reduced / non tip to a server at a restaurant for failure to bring you a drink refill (or even ask if you want another).
The rattlesnake is shaking your ice to try to get their attention.
When you eat at a restaurant and your drink runs dry. The server, for whatever reason, will not come by to give you a refill. You summon the "no tip rattlesnake" by shaking the ice in your glass to try to get their attention. You either do not get a drink, or it takes forever.