It likely means his friends are embarrassing.
And I get it, as far as that goes. Sometimes, you grow up faster than your friends, or you outgrow your friends in some respects, yet you don't want to "dump" them. So you cling to friendships even if doing so is a bad idea.
That said, your guy is being dumb. You're going to meet his friends eventually, as it's not like he can just shove you under a rock every time they drop by. Tell him to man up, set a time, and introduce you to at least a few of them. If they act like jerks, hey, at least he warned you.