Not all dealers do this, but those that do subscribe to the theory that this noise calls attention to the fact that they just got a toke and maybe the rest of the players will "wake up" and do put down a tip also. Some also consider it a good luck omen for attacting more tokes.

So, those that do it are not likely to stop. Also, pit bosses aren't likely to irritate the dealers but ruling out the practice just because some nut doesn't want his cheque to be chipped <G>.