Ben Affleck and his ex-wife, Jennifer Garner, haven't always been on the best terms after divorcing, but lately -- including this weekend -- they're 2 peas in a co-parenting pod.
The 2 exes -- who share 3 children together -- were hanging out Sunday in Santa Monica, where their son Samuel had a basketball game ... and while they were waiting for their kid so they could all leave, BA and JG were laughing something fierce in the lobby.
Take a look .