The G.I.s means basically to have diarrhea. This saying was probably given the name as I am told soldiers stationed in china in WWII got diarrhea when eating local food.
Synonyms for The G.I.s
On this page, you will find 30 slang terms related to G.I.s. Some of the top words include: crap factory, strong bad, cold diarrhea, Rea-Dia, minaya, and 25 more.