Epic games have announced that this week there will be a 22x XP event across all game modes including Horde.
Epic Games' Rod Fergusson announced via his Twitter that the XP multiplier would be the same as the amount of weight he lost in preparation for GDC.
Turns out he lost a 22 pounds leading to a 22x multiplier this week. He had these words to say after;
"Hey all,
Just popping in to say "Thanks for all the support!". I made this public so that the community would motivate me and you have certainly done that. Everytime I look at a donut I think how pissed off you would be if it were only a 3x XP event"
Subject: Gears Of War 2 Fitness 22XP Event This Week 
Mon Feb 28, 2011 5:44 am