Party Host was an extreme difficulty stamp in Club Penguin. To obtain this stamp, you need to have at least 30 other penguins in your igloo.
This stamp was released on July 26th, 2010, as one of the original stamps.
This is not a member stamp, but it is very difficult for a Non-Member to earn this stamp, since they can't open the igloo. They have to be in a server with at least 30 friends, and have them all go to their igloo. This makes it nearly impossible for Non-Members to obtain it, even if it is organized.