trunk monkey
n.—Gloss: a rear gunner in an armed vehicle, caravan, or convoy. Note: Used among military personnel and contractors in Iraq. It’s possible that the term derives from this advertisement from Suburban Auto Group, and others in the same series which first aired in Portland, Oregon, in January 2003. «A “Mad Max” array of mostly white, mostly Western security contractors pulled up to the airport in waves of armored SUVs, some with sirens wailing. Their gunners squatted in the open backs. Sunglasses blanked out their expressions. They were the “trunk monkeys”—security contractor parlance for the gunmen who ride in the back of convoys, aiming their weapons at the Iraqi civilians on the road.» —“Out of Iraq: The Haves, Have-Nots And Dogs” by Ellen Knickmeyer Washington Post Dec. 15, 2007. (source: Double-Tongued Dictionary)
Further reading
Sure, there’s winter, spring, summer, and fall. But the seasons in between have even more poetic names. In Alaska, greenup describes a sudden, dramatic burst of green after a long, dark winter. And there are many, many terms for a cold snap...
Diamond dust, tapioca snow, and sugar icebergs — a 1955 glossary of arctic and subarctic terms describes the environment in ways that sound poetic. And a mom says her son is dating someone who’s non-binary. She supports their relationship, but...
may be related to these auto dealer ads, a web video sensation in 2005.
http://www.youtube.com/watch?v=8avOiTUcD4Y
Yep, I wrote about that elsewhere on this site but didn’t post it here. I’ve updated it now.