Let's say you were invited to a party. Now, would you invite two more people to come before you asked the host if you could?

I just got a phone call from someone who was invited to my mother in laws b-day party saying that two more people were coming tomorrow. Ok, so it's not a big deal. Like Alcia Silverstone says in Clueless, "You just need to hall ass into the kitchen and rearrange a few things." But still! It's the principal of the thing! Don't you think that person should have asked me FIRST? It's not about there not being enough food, but also, I needed to take into consideration that our apartment is not big enough to hold the two extra people...there's already so many people that it's going to be uncomfortable for everyone as is! Lastly, I'm sure the people who were invited by my guest are wondering why they weren't invited by me in the first place (and there are reasons, by the way) which causes a sticky situation for me. I just don't get some people. I would never invite people to someone else's event without asking the host first.

Really, it's not that big of deal. It's just something I would never do.