Learn it. How about party crasher?

I had 5 unpleasant party crashers yesterday. I hosted a new year potluck party for 30 people in my apt- they are all friends and their dates. After dinner, we divided 3 porker groups playing different poker games. One friend asked me if his friends - a couple could come over for poker game. I surely said yes.
Then I found out this couple brought another three strangers. I was a little pissed since I didn't like strangers to my place without any notice. They sit down then took the food and drinks like starving animals without asking anybody. They made themselves so noticeable, people started to make comments even the friend felt uncomfortable. I sort of thought they were pretty rude but I forgave them for the new year.