Tricep:Boob Ratio
The method of telling how much of a girl's bust is made up of fat, by looking at the amount of fat stored in the tricep region.

Scientifically the most accurate method known to the common man. Devised by TheBald.
Guy 1: Mate did you see Steven's new girlfriend? Great set on her.

Guy 2: Check out the Tricep:Boob ratio, it's only because she's chubby.