Having penned a hit single about "Waking Up In Vegas," Katy Perry knows all about the unintended consequences of a late night in Sin City, and as sad as it may seem, she's far from the first person to blow five figures in a night out at an exclusive Vegas nightclub. But in a refreshing twist on the usual debauchery, the $50k that Katy and her BFF Markus Molinari dropped at the 1OAK grand opening on Friday night didn't go to remodel Gavin Maloof's guest cottage or pay off Floyd Mayweather's gambling debts; it went straight to GiveLove, a charity doing humanitarian housing and sanitation work in Haiti.

And speaking of sanitation disasters, Paris Hilton was there!

[David Arquette, Rosetta Getty, Balthazar Getty, Patricia Arquette, Katy Perry, Jason Arashben, Markus Molinari and all other photos via]