I ask you, who among us hasn’t sneaked a sip? It’s only natural, and it is somehow, illogically, preferable to drink most of someone else’s drink than to forget whose is whose. That’s assuming you’re very close with the person - I’ve tried drinking strangers’ drinks and they seemed to be of the opinion that there was nothing worse than that.
What I want to know is, what was Greg’s story going to be before he realized his drink was gone? Now we’ll never know!