The modern version of the term banned. To be benned is to have your access removed from a gaming server, a forum, or a wiki.
User on a gaming server: R U SRS?! U FUXIN N00B!!!!
Admin on a gaming server: Sorry man, but caps lock is cruise control for cool, I'm gonna have to ben you.
User on a forum: Fuck you all, you're all a bunch of fuckers. You think theorizing is cool, but it's not. You're just blinded by multiple theories that don't match up.
Admin on a forum: I'm not even going to warn him, I'm just going to ben him.
User on a wiki: ASH KETCHUM SUCKS BALLS. MISTY IS A BITCH. BROCK IS BLIND!!1!1
Admin on a wiki: Time to ben someone.
User on a wiki: Fuck I just got fucking benned.