Words said by our beloved marvel character Loki before A FUCKING UGLY PRUNE STRANGLED HIM TO DEATH (even though most the fandom know he's probably still alive amen to our beloved trickster)
IT IS ONE OF THE MOST TRIGGERING LINES FOR ANY MARVEL FAN SAME GOES FOR "I don't wanna go, I'm sorry" said by our beloved peter Parker aka spider man THE RUSSOS CAN FUCK OF WITH THEIR BULLSHIT OF TOM HIDDLESTON IS TOO OLD TO PLAY LOKI BECAUSE WE ALL KNOW HE. IS. ALIVE.
This is an expression related to the blueing of a gun - specifically a high-end shotgun. In the South especially, a finer shotgun would have a "blueing" or a "blue" of the steel that was accomplished by way of the quality of the steel and the effort of the person who owned the gun polishing it. "Shotgun shine" is a simplification/symbolism of this concept and a way of saying that a person has a killer instinct; however attractive they may be. It's not necessarily a positive expression, and surprising that in the nearly 25 years since Alabama 3 used it, and since the Sopranos used it in this manner exactly, that no one else has put it on Urban Dictionary.