Mary-Kate and Ashley Olsen celebrated their birthday in style -- with a Summer Olympics-themed birthday bash in the Hamptons!

The child stars-turned-fashion designers turned 29 on Saturday and spent their birthday with day of celebrating with friends and family in the Hamptons.

The twins' Olsen Olympics' theme party was complete with two warring sides, Team Mary-Kate and Team Ashley and the hashtag #OlsenOlympics. The teams even had their own T-shirts – red for Team Mary-Kate and blue for Team Ashley. At the fete, there was a Happy Birthday banner with the Olympic logo, medals engraved with either Mary-Kate’s and Ashley’s name, an obstacle course was constructed with cones, tires, and beams. The soiree even had a dunk tank, according to the Daily Mail.

We assume partygoers had a blast -- although judging from MK&A's expressions, a good time was not had by all.

But the real question is: which team won? Team Ashley!