THINGS are really hotting up in the Playboy mansion - and we've got video evidence to prove it!

Hugh Hefner's three gorgeous girlfriends may deny reports of catfighting at their fabled abode, but we've got proof relations can sometimes be strained between the babes.

In an exclusive interview as part of our Heyman Hustle series to be broadcast next week, Bridget Marquardt, 34, and Holly Madison, 28, were caught totally off guard by host Paul when he asked them their opinion of Hugh’s third girl Kendra Wilkinson partying in Cabo instead of working.

"Screw Cabo," Holly exclaims but then tries to laugh it off, while Bridget chimes in: "She's on vacation while we're here working?"

While the Girls try to then joke around about it, you can tell they did not know Kendra, 23, was laying out in a hot bikini in Cabo while Holly and Bridget were hard at work judging the Playboy 55th Anniversary Playmate search.

See their reaction in the video HERE via The Sun