Something said as an after thought, either approving of something or not agreeing. Also used to show surprise, or mock somebody/something.
Has developed into many different variations (such as bloofies, bloofers, doosh, blam) in order to fit into context or to include variety.
Matt: Is this? (pointing to 24 pack of good beer he just bought)
Matt: Is this!? (pointing to a micro brew keg)
*at the bar...an ex girlfriend walks in...*
Matt: My ex just walked in dude!
Shawn: Ba-blam! Let's bounce.