The nickname Dirty Boat Guy or "DBG" is associated exclusively with the US Navy's Special Warfare Combatant-craft Crewman (SWCC, pronounced “swick”). SWCCs are more commonly referred to as Naval Special Warfare “Boat Guys.”
The true and complete history of the DBG nickname is unclear, but the battlefield bravery and late night debauchery associated with the title live on in infamy…
“Grab your kit, check your weapons, and fire up the boats. We’re expecting heavy seas and rain tonight… time to get your Dirty Boat Guy on.”
“I realize you Dirty Boat Guys are going out tonight and that’s fine, but I better see your asses here ready to drive fast and shoot hard by 0600.”
“You did what? Oh bro, you Dirty Boat Guy'd the hell out of that chick!”
It is said of the situation where a person has the bad luck to make contact with his testicles against an undefined surface or object, intentioned or not.
Given the nature of the word, it is more appropriate to design cases where the interaction is made with a moving object, for example, a ball.
Although it is extremely painful for the victim, it tends to be considerably funny to people who witness it.
Today in the baseball game the pitcher took a nutshot; the baseball hit him in the nuts.
Man, I just watched the funniest nutshot video ever.