Pax may mean "peace" in Latin, but Pax Jolie-Pitt was all about war during a shopping trip to a party supply store with his mom Angelina Jolie and older brother Maddox in Hollywood on Thursday.

In a hilarious photo (see more at X17), the movie star and director 36, cracks up as Pax, 8, wearing fatigues, aims a toy rifle directly at the camera. (Although on hand for the excursion, his older brother Maddox, 10, wasn't pictured.)

After spending much of 2011 abroad, Jolie and love Brad Pitt and their brood of six have been spending quality time in L.A.. Pitt, 48, ran errands with Pax in the sidecar of his $11,600 Ural Tourist motorcycle on New Year's Eve, and the busy parents had a night to themselves partying (and dancing!) at Jonah Hill's 28th birthday party, where newly single Zooey Deschanel was also in attendance.

But on Thursday, Pitt stepped out in Beverly Hills in a bizarre black jumpsuit -- and a cane! "He tore his MCL," a source told Just Jared, explaining that Pitt injured one of four ligaments that stabilizes the knee joint.