Pre-christmas cock-up
A condition (or an incident) where you get unintentionally very, very drunk and more or less accidentally end up having sex with one of your colleagues. At every fucking company christmas party.
Oh look at so-and-so, she's leaving with yet another man from the engineering department. Didn't she go home with X last year? And, she's very, very drunk. What a pre-christmas cock-up. Again.