A bump is when you volunteer to take a later flight when you are on a plane that is overbooked. The usual Domestic "Bump" is $300.00 a hotel room if overnighting, a meal voucher ($10) and **sometimes** you will get put in FC for taking the "bump". If you are skilled at finding oversold flights you can rack up some big $$. I do not look for bumps but one lucky weekend I made $900, got a free hotel room, cab ride, dinner, and all in FC (I was there anyway though)