One who casts off the restraints of a conventional life to pursue their passion(usually something dangerous and off the wall like base jumping, rock climbing, surfing etc.) Often you will find them living in vans, buses, caves or tents. Usually broke but always smiling.
Girl: Mommy, I neverwant togrow up. Mom: Well Dear, learn to climb, buy a van and become a dirtbagger.
It is when a man puts his penis inside his girlfriend's, OR BOYFRIEND'S asshole, while quoting Steve Austin lines, pounds rapidly in their anal cavity. Suddenly, the pitcher feels a sharp pain in his penis tip, so he pulls out, and what does he find? A little chunk of shit lodged in his peehole. That, my friend, is a Dirtball Digger.