Solid concept! I had some trouble "giving" the drinks to the customers and the customers not sitting properly, but the models are really cool and the color mixing mechanic is neat. I agree with @anUncreativeGamer about the pink/purple thing, but otherwise all-around this is really neat.

...I think you might be color blind because red drink + blue drink is not pink. It's purple.

Otherwise the game is actually pretty cool, aside from some problems like how some customers have their models not on actually where they are, and how serving one poison instantly ends the game.

I especially love the character designs and the funny posters on the walls.