Wtf? It seems like there is no way to remove those automatically generated "participates in bla event" posts on your wall if those events are public. Shit doesn't even show up on my timeline anywhere. I despise that clunky piece of shit website..
/it's not even in my Activity Log/on my timeline, but it's still all over the place in other people's feeds (I have my gf's account logged in on my tablet)..
i found out about this recently as well. was invited to a group as a joke from internet friends and was just being offensive when my real life friends started liking my stuff. i was talking (joking) about how my mom was a pot addict and couldn't leave home without it. had no idea real life peeps could see that. but ya, really annoying stuff. no privacy on facebook.