Celebrities sure now how to throw a party!  Invite your best friends and add in a few of your favorite musical artists and wait for the magic to happen.

That's what happened at a private bash to celebrate Reese Witherspoon's 40th birthday.

Dozens of 'A-list' celebrities were on hand and both Keith Urban and Taylor Swift took to the stage to perform for the birthday party goers and birthday girl.

Reese Witherspoon even took to the state to duet with Keith Urban on "Sweet Home Alabama".

Wonder if we can get Keith to come perform at our next birthday bash??