Credit: Chris Polk/FilmMagic for Bragman Nyman Cafarelli

Don't expect everyone at the Kardashian-Humphries wedding to be perfectly behaved!

The bride-to-be's stepbrother, Brody Jenner, is planning on letting loose during Kim Kardashian and Kris Humphries' celebrations Saturday night. (Brody's father, Bruce, has been married to Kim's mom, Kris, since 1991.)

"Getting a nice 10K run in before the long drive up to the wedding," the 27-year-old former Bromance star tweeted Saturday. "Congrats, Kim. Love you." 

But Brody -- who has been romantically linked to Avril Lavigne since 2010 -- alluded to his partying plans for Saturday night. "Oh yeah," he added. "And it's my birthday at midnight. RAGING tonight!"

Kim's brother Rob also seemed up for some fun. He retweeted Brody's tweet, adding, "I'm with Bruce tonight and we are gonna RAGE!!!"

Humphries, 26, joked with his future brother-in-law earlier about whether he should go with a "mustache or no mustache for the wedding?"

Rob's advice for the NBA star? "Get a hair cut and shave your mustache," he said.

Kim, 30, will probably appreciate a clean-shaven beau. Her pre-wedding rituals? "Spray tanning, nails, a midnight call to Anastasia to do my eyebrows," she told Ryan Seacrest Friday, adding that she feels completely "calm" about her upcoming "I do's."