Best way to shut down the table coach without tapping the glass?

[CinnamonWind]

I often find myself at tables where someone decides to be Mr. Poker. They start to ridicule other players, or they say idiotic things like "some of us do this for a living" and so on.

How do I tell these people to kindly stfu and stop making people play better without alerting the fish? I've tried:

*cough*
"please don't tap the glass"
"stfu and play, whiner"
"let's just play cards, k?"

And so on ...

Is there a good line that lets the idiotic coach/critic/whiner know that he's probably screwing up everyone's action by being such a yapper?

(Clever or funny are fine, but also some effective lines would be good!)