Happy birthday, Scooter Braun! Justin Bieber, Ashton Kutcher and wife Mila Kunis and other A-list celebs turned out to celebrate the manager/entrepreneur's 38th birthday Tuesday night in West Hollywood at the private club San Vicente Bungalows. How chic!

Bieber and Kutcher may be an odd couple, but they both work with Braun -- the baby-faced broker managing Justin's career, obviously, and partnering with Ashton on a venture capital fund. Hey, he's gotta put all that money somewhere!

Ashton famously invests in the tech industry and the two even partnered on Washio, an "Uber for laundry" app, recently.

Guests were dressed-down, Justin wearing throwback overalls with the straps undone, super baggy in the legs, embellished with cartoon drawings. Super-skinny Ashton wore the Silicon Valley look -- button-down with jeans and Allbird sneakers. Even Mila didn't bother with makeup or a dress -- just her hair pulled back in a knot with a grey sweatshirt and jeans.

Noticeably absent was Mrs. Bieber ...