How does Chelsea Handler wish her best friend Reese Witherspoon a happy birthday? By sending her a nude, of course!

As the actress turned 40 earlier this week, Handler took to her Instagram where she posted a photo of herself in the nude (aside from some black knee-high socks), covering just her unmentionables.

"Happy Birthday @reesewitherspoon," Handler captioned the racy photo, which can be seen here, and in the Entertainment Tonight clip below.

Handler was one of the many celebrity guests included in Witherspoon's 40th birthday celebration over the weekend at hot spot Warwick in Hollywood, Calif.

"The Legally Blonde star — who rented out the entire venue to host a Mardi Gras–themed party for her big day — was also feted by pals including Kate Hudson, Jennifer Aniston, Justin Theroux, Courteney Cox, Matthew McConaughey, Robert Downey Jr., Isla Fisher, Conan O'Brien, Chris Martin, Tobey Maguire and more," Us Weekly reported on Tuesday.

During Witherspoon's party, the mother of two was treated to performances by both Taylor Swift and Keith Urban, who performed hits, including “Shake It Off” and “Sweet Home Alabama,” as she and her friends partied until 2 a.m.

“She had the best time and didn’t want the night to end,” an insider told the magazine.

Handler and Witherspoon have been close friends for many years, and in 2013, following Witherspoon's shocking disorderly conduct arrest, Handler came to her defense.

"She's doing fine. She's doing fine, you know?" Handler told Entertainment Tonight. "She was just trying to protect her husband, so...I mean everybody makes mistakes, so it's not a big deal."

During a trip to Atlanta, Witherspoon and her husband, CAA agent Jim Toth, who was behind the wheel at the time, were pulled over, and after Toth was given a sobriety test, Witherspoon became irate, and infamously pulled the "Do you know who I am?" line. In turn, both she and her husband were arrested (Toth was arrested for DUI).

To see more of Handler's nude antics, check out the video below.