Excited, pointless and always somehow self-referential verbal-diarrhea. (See ANY Tarantino interview.)
Not an example of usage, examples of actual masterblathering:
"You don't have to tell me how cool I am, listen to ME tell you how cool I am!"
"Did you see me at Madison's party? Everybody was waiting for me to do something cool, I know, but I made them wait until Madison was right next to me. Did you see it? I was SO AWESOME, dude!"
"So I watched this movie once called "City on Fire" at the video store they let me work at and I thought "Shit, nobody's seen this! If I can get Harvey Keitel and that funny-looking guy from Fargo I can totally rip off my first movie!"