Behold The Power Of Pete Wentz

Ashlee Simpson partied like it was 1983 over the weekend to celebrate her 23rd birthday. Despite being a zygote when leg warmers, lace gloves and Atari video games were all the rage, Ashlee threw herself an '80s-themed party at the happenin' hot spot that is her parents' house. Among the guests were her big sis Jessica, Yo Momma kingpin Wilmer Valderrama and, of course, her boyfriend Pete Wentz.

Speaking of Pete … he must have given Ash a kick-ass birthday present 'cause she went totally nuts trying to get his attention at a Fall Out Boy show last night at Paramount Studios in Hollywood. She was caught on camera by TMZ screaming and jumping around like a star-struck schoolgirl and trying to start a mosh pit while her boy was onstage performing "This Ain't a Scene, It's an Arm's Race." When she couldn't seem to catch Pete's eye with her antics, she grabbed her friends and made a beeline to the front of the stage, to dance in his line of sight. But when the crowd around her got too rowdy she complained she was getting "really hurt" and left the danger zone. Guess she didn't really want to start a mosh pit after all.