Why Does My Girlfriend Pee My Bed When She Gets Drunk?

The same reason you pee in the bathroom....she relaxes her bladder muscles. When someone is drunk and asleep, they can often miss the signals most of us get during the night that wake us up to go to the bathroom -- resulting in a round of sheet changing, blushing, and wishing one were a thousand miles away. And, of course, alcohol in and of itself, is a diuretic. Good luck with that.

Alcohol not only increases the rate of urine production, but it also knocks you out.  Then, during the night when your bladder is full from drinking, you aren't able to respond to it normally because you've been drinking.  You bladder can only hold it so long, then it opens the floodgates and you have a wet bed.