I may be going to a birthday "party" this Saturday night. It's for my SO's friend. I've met him a few times but I don't really know him. We both know each other but aren't friends. Anyway, this gathering is going to be a bunch of people at a girl's house to eat, and then somewhere somehow playing dodgeball. For some reason, I doubt anyone is going to be bringing gifts for him, because it isn't really a birthday party and the people going aren't really the people who would do that. Plus, when my SO told me about it, he just said it was people getting together for [said friend]'s birthday. He made it seem pretty casual.
So finally, am I required to bring a gift of some kind to this? I don't even think my SO will be bringing one, but I'm not sure if it's still rude not to.