Bad Santa by Jordan Silver

Grant Lorenz is a foul mouthed marine who’s having a very bad day. A judge has ordered him to do a stint as the mall Santa or go straight to jail. Now he’s mad at the world and have a chip on his shoulder, and anyone who gets in his way is going to catch hellfire. Then the new boss lady gets in his face and he decides to teach her a lesson.

Josephine Bissette is an overworked store director whose Santa just bailed right in the middle of the Christmas season. She gets an offer and since she’s stuck, she has no choice but to hire the disgruntled hard nosed man who’s standing in her office looking like he’s just chewed nails for lunch. She’s out of patience and not much interested in anything but getting through the holiday from hell, and the overgrown ape standing in her office trying to get under her skin isn’t helping.

She sends him packing after five minutes, but the man who didn’t want any part of this gig suddenly decides that here is just where he wants to be if only to make her holiday as miserable as his.