What does SWAG mean?
Swag has many meanings depending on the context. It is the source code of the program language Pascal and it is the acronym for the Special Warfare Group in the Philippine Navy.
It is also used to name many things, such as a music album by Gilby Clarke and a reality show in England.
Anyway, if you see SWAG online on Twitter, Facebook, and while texting, SWAG usually means "Scientific Wild Assed Guess." However, we prefer the lesser known SWG acronym. SWG which simply means "Scientific Wild Guess."
In any case, SWAG is referring to Scientific Guess, which means that you are voicing an opinion based on some known scientific facts, and assuming others, to come up with the best answer - or guess. Some people also refer to it as an educated guess.