A small regex pattern could cover your numerous Partyroom nick matches.

$regex($nick,/(Partyroom?[0-9]?)/))

I'm not par with regex quite yet and I'm sure someone will jump in and bust my chops for my horrible example but it should get the job done. You could possibly polish it up a little bit with an escape character (Which, I'm assuming, is the one of the back slashes. (/ or )) to replace the any character match (?) with a more specific character match. Seeing as the brackets [ and ] are used by regex to represent character classes of sorts; it makes it a whole nother ball game to mix them into the matching process.