LOL - it seems that this time of year is facebook addiction time. a few friends badgered me as I wouldn't touch Myspace, this seems much more up my alley, although for the last 30 minutes I should have been sleeping, I've yapped and yammered on the damn thing. And now I've joined the reefing group. No, not that one, THIS one.
As for the "tagged" - that just means your name was noted in another picture, story, etc. Not tagged in that way. Poked I'd be more concerned about
But in the end, all that means is you get a message saying "You've been poked by SuchandSuch, do you want to poke them back?" - so nothing TOO much to fear.