Nice birthday present, Ben!

The just-turned 46-year-old celebrated with Playboy model Shauna Sexton over dinner at Nobu Malibu, according to reports. After a sweet dinner with his kids Wednesday night, it appears Ben decided to mix it up a bit with a rendezvous in Malibu Thursday evening. The Batman actor reportedly met up with a much-younger 22-year-old hottie.

The Virginia Beach native could have been taking a dinner meeting with Ben about an upcoming project or perhaps a job interview for a nanny position in charge of taking care of Ben's three kids. Whatever the case, Affleck's girlfriend Lindsay Shookus wasn't there. It's a little fishy that the possibly-pregnant TV writer wasn't in town for Ben's big day, which certainly leads us to believe the two could have broken up.

Seems ex-wife Jennifer Garner wouldn't be happier if the two went their separate ways -- she's not a fan of Lindsay's according to recent reports. But would she really prefer Ben hook up with Playboy model? Doubt it ...

The sexy "single" (according to her Facebook page) model is "sarcastic," wants a guy "with a good sense of humor" who is able to "compromise but doesn't sell himself short." That's BEN!

And right now the actor's not selling himself short ... he's back in treatment after Jen required him to get therapy again if he wanted to maintain visitation with the couple's kids - Seraphina, Violet, and Samuel.

But seriously, is dating a girl less than half your age really the way to go, Ben? We're guessing the vote on this is going to be split down the gender line ...