An abbreviated version of the meme "2/10 Would Not Bang" which is giving a picture of an extremely attractive woman a 2 out of 10 for minor flaws. It is meant to be a joke and even a compliment that the person is so attractive, giving her a 2/10 is obviously not a serious rating.
1. (Adj) Term Coined by the US Military Servicemen decribing any person who is unattractive stateside, becomes attrative during deployment overseas, due to the law of scarcity, and returns to being grossly unattractive upon return from deployment.
similar to the 10@2 rule, but for a longer duration.
2. (n.) any person who can can be sescribed as a 2-10-2:
2 at home
10 in the desert
2 when they get back
(1)soldier1: dude, stacy looks so hot!
soldier 2: i don't know dude; 2-10-2.
(2)marine: man, i'm so desperate that i could hit a 2-10-2.
The second letter of the alphabet, the 10th letter of the alphabet... if you are unfamiliar with that, here's the alphabet, with the second and tenth letters capitalized...