The moment newly-arrived Marines entered the jungles of Vietnam, they were faced with a question from the most persistent recruiter. The call of the Blue-Eared Barbet, a bird indigenous to southeast Asia and beyond, has a distinctive, high-pitched warble:
In the elephant grass, there lives a bird whose call sounds like reeeuhuuup, and of course Marines call it the RE-Up Bird. As I am sure you know, re-up means to re-enlist, an idea not popular with the Marines over here.
It was the question no one was ready to answer right away. Luckily for the soldiers and Marines in the Vietnamese jungles, night time brought out the Tokay Gecko, who had the perfect answer to the Re-Up Bird.
Elbert Franklin Evans recounted his earliest encounters with Vietnam's nighttime sign-countersign between the Barbet and the Gecko in his 1997 book, "Night On The Perimeter:"
"I heard the snickers from the soldiers on the bunker on my left. They enjoyed this jungle sonata, which echoed their own sentiments. Re-up? F*** you. You found humor in unlikely places in the bush, and this small bit of humor was peculiarly calming."
Vietnam veteran John Podlaski writes extensively about the sounds of the jungle at night on his blog, which is named after his book, "Cherries, a Vietnam War story," about his 1970 deployment to the country.