Bwaha!
But perhaps he wasn't referring to a drink called Pink Panther... I found two other slang definitions that may be more interesting. And disgusting. I
almost want to apologize for posting them:
pink panther: A heterosexual male who uses a homosexual manner to pull women. This is used to such an extent that many people suspect him to be gay.
-Did you see how camp that bloke was, he must be gay.
-Nah, he's just a pink panther.
pink panther: when a chick is on some guys tip, and she's giving that mean b.j., right before he busts, she bites down hard enough to draw blood, thus mixing red(blood) with white (gentlemens relish), makes the color pink. similar to that of a pink panthers tail.
maria: you like that?
man 1: heck yes!
man 2: DO IT!
maria: -chomps down-
man 1: owwwwwwwwwww!!! ahhhhhhhh. i love you baby!
man 2: she just gave you a pink panther.
maria: bitch.

...Dear god...