Night Strike wrote:
invited that player to the game, or your password was too easy to guess. Next time, I'd use invites instead of PMing passwords.
The downside to this of course is that if an invite expires or is declined that spot will open up to other players.
I would probably tell the player that invited the other player that you didn't want the other person in the game. As long as you're polite about it, most people will just say sorry and remember it for next time. If they don't, well that's probably a person you don't want to invite to your games anyway.
Also, I've been asked to drop a game that I joined that the creator was trying to invite other people to. I dropped the game when I was asked. I think most people would do this, also.
That said, other times when I've accidentally "snuck in" to a game, the people just play it out and we all got a chance to meet new people. It all depends on how badly you want to have control over who joins your games.