Three solutions to this:

1) Wait until he takes a good long sip, and then say, "You really shouldn't be so rude to people handling your drinks. Does that taste funny to you?"

2) Before you even hand it to him, throw it in his face. You may get fired, but at least that guy got what he deserved.

3) If he's not good looking himself, say "No, but I'm sure you know how that is, huh? Did someone have rough high school days, hmmm?"

I would go with number 1. Just saying.

But dude that sucks. That guy is a condecending douche.

a complete stranger just upped and said that to you? wow...some people have to learn that if they have nothing nice to say, they really shouldn't say anything at all....i would have told him to take the log out of his own eye before judging me...