From now until September 16th, players can contribute to the BAM kill count and work toward the ultimate goal of 5 million BAMs dead in 21 days. Each day players log in during the event they will receive a special loot box that will contain five federation bills and a chance to drop bronze, silver, or gold BAM tokens -- tokens that can be exchanged for costumes, accessories, and even weapons exclusive to this event. For a look at all the possible rewards, check out the BAM Killer program.
[Source: En Masse press release]