@SuomiJules if you don't have the late night bars, then find some very attractive object that'll encourage them to hang around the party room. Doesn't matter what it is. If you don't keep them in the room I've found they wander all over the house and end up getting bored and someone will leave without the required moodlet.
As far as the strong arm badge is concerned. I think it is the patch level that's the problem. I achieved it on patch 1.55. I don't use Origin so don't have to be stuck on patch 1.69.
