Meet Jody. Jody decided to shirk his patriotic duty and stay home while you chose to serve your country. Jody is lying in wait, plotting to steal your girl when you’re away. It’s easy: Jody will swoop in, console her when she’s lonely, then slowly fill your boots simply because he’s there and you’re not. He’s the original “Mr. Steal Your Girl,” and he is every soldier’s worst nightmare

Everyone’s heard of a Jody: whether you’ve met one, had a brother come to you for advice about one, or seen one in your favorite military move. “Jarhead’s” infamous “Deer Hunter” scene did him the most justice, when Brian Dettman thought his wife had sent him the war classic on VHS, which had instead been taped over with homemade porn featuring her and Jody.

But where did Jody, scourge of the deployed soldier, come from?

The U.S. military’s use of term dates back to roughly 1939 when it was introduced to the U.S. Army by African-American soldiers during World War II. Originally, “Jody” was “Joe the Grinder,” and blues singers used to croon about him — a disreputable man who cuckolds prisoners and soldiers by stealing their wives and girlfriends. While he’s Joe simply because it’s a common name, the “Grinder” comes from the 19th century slang for sex. Jody literally grinds up on, and then, in your girl.

By the end of the war, the name had been shortened to Joe D., then Jody, which stuck. And everyone knew who Jody was. The idea of him even worked its way into cadences.

Ain’t no use in going home
Jody’s got your girl and gone
[…] Gonna get a three-day pass
Just to kick old Jody’s ass.

— U.S. Army marching cadence, circa 1944

Tad Tuleja and Eric A. Eliason, authors “Warrior Ways,” explain that Jody permeated military culture after World War II, not just because men were concerned about civilians stealing their women, but because they were keenly aware of their own “waywardness.” If a soldier could seek the company of another woman while in theater, there’s no reason why his wife or girlfriend couldn’t or wouldn’t do the same.

“The same soldier who curses Jody one day may on another occasion spout the common saying, ‘What happens [on temporary duty assignment], stays [on temporary duty assignment],’” they write.

It’s essentially the military equivalent of “what happens in Vegas, stays in Vegas.” And while some soldiers can get away with cheating scot-free, what Jody does happens at home, and — there’s no escaping that.

The good news is, at least in most marching cadences, Jodies are far lesser men than service members. So if Jody does steal your girl, you can always kick his ass.