I'm a ramblin' man refers to the process of ending a sentence with a flourish, generally after a long, non-sensical rant or after a moment of indecision. it can also be used as a greeting amongst close friends. started in bloomington, indiana, this phrase alludes to Lemon Jelly's song "Ramblin' Man".
"Hey Bob, where do you want to eat tonight?"
"I dunno. I'm a ramblin' man."