Naw, CuriousM, I think it’s the licking of the bottle necks that seems sexual. After all, you don’t get drunk licking bottles. The gesture is not a drinking gesture. It is intentionally reminiscent of fell atio. It’s a clue that their idea of partying DOES involve, if not picking up guys, at least teasing and flirting and seeking attention from guys.
Anyway, my reason for commenting is I’m curious what the left one’s doing with her fingers. She could be doing a “zipper” motion, as in “my lips are sealed to this alcohol” (maybe she’s breastfeeding the baby?) or it could mean she’s the naughtiest one in the group and is holding e or LSD as her buzz-of-choice because she doesn’t like drinking. Or maybe she’s suggesting silence, like “I will never tell anyone the events of tonight”. Anyone?