Umm...I hope that isn't a rhetorical question...cause i think im gonna try to answer it...
Cause, first, they are drunk. And statistically, SOME women find crude humor funny. And eventually, if the drunk (and probably horny) guys look long and hard enough, they will find a woman who works at the front desk (somewhere) who enjoys crude humor. With the hopes that they will get lucky.
I do enjoy some crude humor and yes I work at the front desk...but what makes them think that they could ever get lucky? The jokes they were trying to pull were at the maybe 5th grade level.....