RIM has sent out invites for a BBM Ugly Sweater Fan Night happening on Wednesday, December 21st. The event is to “to celebrate the holidays and BlackBerry’s latest apps…for a night of food, drinks and holiday cheer”.

The party is likely to help promote the release of the Ugly Sweater expansion pack to the popular Avatar Builder app. We’ll try and stop by and see if Mike or Jim bust out an ugly sweater. Fans can follow the conversation from the event on Twitter with the hashtag #BBMUglySweater.