I'm not sure what's harder to believe, that Gwyneth Paltrow has just turned 40, or that she's duetted on a rap with Cameron Diaz, making fun of their close friend, comedian Chelsea Handler.

Diaz and Paltrow appear on camera, saying that they have heard that Handler is getting a new studio, and then launch into a rap, performed by Paltrow with the beatboxed beat provided by Diaz. They cover a variety of themes during the rap from Handler's promiscuity to her drinking habits and various taste in men with the final line exposing that “50 cent told us you like it rough” amid pelvic thrusts towards the camera.

It's unsure whether the pair intended this ever to reach light of day, or merely wanted to send it to their friend. However, Handler clearly considered the good humored jibes to be a less embarrassing for her than the thrusting would be for Paltrow and Diaz and consequently popped the video online.

This isn't the first time that Gwyneth Paltrow has rapped to an audience, she also did a short section from NWA's 'Straight Outta Compton' on the Graham Norton Show in 2007, after confessing her love for '90s hip-hop.

Paltrow has had a fun week with friends Beyonce and Jay-Z. Beyonce gave her a birthday shout out at one of her shows and then she spent a night celebrating her birthday with the couple, as well as Diaz, Handler and numerous other friends in New York.