The tension between Brandi Glanville and Kyle Richards ramps up on next week's Real Housewives of Beverly Hills.

In the promo video for Season 4, Episode 4: "Irked at Cirque," the ladies take an acrobatics class at the Cirque School. 

"God, you've got the tiniest waist," Brandi Glanville tells Carlton Gebbia when they're in their tight workout clothes. "No, it's because I've got big boobs and a big ass," Carlton replies. Okay, then.

Kyle Richards's husband, Mauricio, addresses the rumors of his alleged infidelity, saying, "Let me tell you something  any of these fking girls can do a lie detector test with me tomorrow, and no problem."

Then, Brandi tells Kim Richards about what Kyle supposedly said about her. "Yesterday, I'm getting chased down in Calabasas by the paparazzi, saying Kyle Richards called me a bully," Brandi tells Kim.

"It just sucks to be called a bully in front of my children," Brandi later tells Kyle, who replies, "Enough of this mean, mean talking, and mean... I can't take it."

Finally, there's more drama between Brandi and Joyce Giraud. "When I'm on my period, I'm a total bitch," Joyce tell Brandi, so of course Brandi replies, "Are you on your period now?" Ouch.

Source: Bravo