Heading "out the gate," or literally through the wire, and entering hostile territory while on a combat patrol, such as in Afghanistan or Iraq. "Out the gate" is also the terrain which is beyond the fencelines / walls of your compound.
Being a grunt, I'm out the gate each and every day.
I've got more time out the gate than you do in the fookin' Army, dude.
Yeah, he was out the gate when the IED got their tail vehicle. Damn.