What is a Jody bar?

In the US Military, a "Jody" is a generalized term for any man who stays home while everyone else goes to war. He gets to enjoy all the things service members are missing, more specifically the girlfriend back at home while the SM is away on active duty. The reason that they're called Jody specifically dates back to black soldiers in WWII. They took a character from old blues songs named Joe the Grinder (or Joe D. Grinder) who would steal the ladies of inmates and soldiers, and clipped his name to Jody.