>>2293563It may start out as regular poker, only becoming strip poker after the girl's lost all her money.
Maybe she hid a bunch of lewd photos of herself in an old photo album thinking they'd be safe, but her mom/roommate/sister submitted the album as a prize for a poker tournament.
Once she's out of money, she can't just turn around and give up, since some stranger is going to end up with a bunch of blackmail over her, and she also assumes that she can win without losing too much clothing.
After that, it's just a matter of sunk-cost fallacy that keeps her betting.