Military scout sniper slang for "Sophisticated Wild Ass Guess"
Used when there is not enough time to make proper calculations for the exact shot.
The shooter will make an educated (sophisticated) guess as to the leading of the target, the range, wind, etc.
The hostiles were moving in too fast, I didnt have time to make the proper calculations, so I just estimated the lead and range on the target and hit him! - Nice damn SWAG man!