Credit: John Shearer/WireImage.com; Denise Truscello/WireImage.com

Nicole Richie and Khloe Kardashian go back -- way back -- and the raised-in-Hollywood kids aren't afraid to take weird jabs at each other in the public forum of Twitter.

The stars, who frequently chat via the microblogging site, mysteriously teased one another on Wednesday and Thursday in a faux "war" that maybe only they could understand.

Late Wednesday, Kardashian, 25, exclaimed "Someone is on fuego tonight!!!"

Richie, 28, replied, "AND THAT SOMEONE IS ME!"

Kardashian then posted a photo of her mom, Kris Jenner, at a basketball game, telling Richie "this one is for you little lady!"

Richie retorted: "my favorite kardashian," presumably praising Jenner. She then added, "PS youre going way down the list.... but its fine, youve hated me since we were 7."

"Karma is a bitch!!!!! The tables have completely turned," Kardashian sassed back. "Just when you became my number 1 i am now your number 7. A girl shall settle... I have no one to blame but myself."

Kardashian (daughter of late Hollywood lawyer Robert Kardashian) explained her celeb-kids friendship with Richie (daughter of singer Lionel Richie) in a recent interview: "My best friend was Nicole Richie growing up," she told PR.com, "and we went to school with the Hiltons. I've grown up around all of these [famous] people."