It is a popular term used amongst gamers. A lot of people (especially those on Quakenet or GameSurge) use IRC channels to set up online game battles between clans. When the clans fight, it is called a "scrim".
Unfortunately, many (particularly new) people in the gaming community think that IRC (or 'mIRC') is purely invented for the sake of scrimmages, therefore, many people use the word expecting everyone else to understand what they mean.
Hamilton: You can use the resources in
this thread for help finding a channel.
Regards,