A military term referring to the process of taking an FNG downtown and getting him trashed. This traditionally happens in Korea, but it could be adapted for a number of overseas locations.
The primary goal of a green bean (or green beaning as it is often called) is to get the FNG accustomed to the strength of the local liquor (usually soju) while making sure he don't die, get arrested or bust curfew.
1: Hey, does the FNG want to go up to Seoul with us?
2: No, he's still drunk. He got green beaned last night.