At 2:30 a.m. on Sunday, Britney Spears' longtime pal, Alli Sims, was served with legal papers concerning the custody battle between Spears and her ex-husband, Kevin Federline.

Leaving a hot party at a private home in the Hollywood Hills, Sims got served by Aaron Cohen of IMS-Security.

"Alli was really shocked and covered her face," an observer tells People. "[She was] really distraught and said 'Oh my God.'"

No word on if Sims or anyone else then busted out any memorable quotes from the 2004 dance-off classic You Got Served.

We're guessing not, unfortunately.

Britney Spears, who was also at the party, did not witness the serving of the papers, according to the observer.

The papers are a deposition subpoena sent by Kevin Federline's lawyer, Mark Vincent Kaplan, compelling Sims to testify about Spears's parenting skills.

Sims, who has known Spears since childhood and is regularly at her side partying in Los Angeles, recently told People:

"[Britney] is a wonderful mom and she is so hands-on... Britney loves those babies to death. And they adore her."

Oh come on. The only thing she's got her hands on is Matt Encinias.

On Wednesday, Kevin Federline filed for primary custody of the couple's two sons, Sean Preston, 22 months, and Jayden James, 10 months.

A source close to Federline said recently that the would-be rapper has been worried about Spears's behavior and thinks she may be exposing the boys to "unnecessary risk."