Three ways to tip the dealers — all of them are just a bet made on their behalf.
Pass Line, for the dealers
Say it"For the dealers."
Win: Point
Lose: 7
Place a chip just outside your own bet, before the come-out, and say it as you do.
Hardways / prop bets
Say it"6 hard, two-way."
Win: pair
Lose: 7
Give 2x chips to the stickman to place a prop bet for them: this one is a hard 6 for you and the dealers both.
Place bets
Say it"For the dealers." + "Player control."
Win: Point
Lose: 7
Adding "player control" brings a twist: the dealers' bet is left on until you instruct otherwise, rather than being cashed in right after it wins. Some casino rules might still require dealers to cash it in sooner regardless.