Jack-speak for ape.
Comes from an excellent piece of slash fiction called "Dr. Jackson's Diary" that is loosely based on the hit sci-fi series "Stargate SG-1." Although no longer available on the net, it is possible to find this gem if you know who to ask, as it still has a small cult following.
As suggested by the title, this piece of fanfiction is written from the point of view of Dr. Daniel Jackson, an archaeologist and linguist working in the top-secret Stargate Program which is operated out of Cheyenne Mountain in Colorado Springs Colorado. The diary chronicles and entire year's worth of missions, misadventures, and madness.
This fic is generally accepted as rated NC-17 for language and content...read at your own risk.
Quoting from "Dr. Jackson's Diary" 'May: Planet of the Not-Monkey' by Anais:
"Hey, hey--" Jack said, wiping his eye for the forty eighth time. "NOTHING on the MALP reports suggested we were being sent to the planet of the--" he paused. I mouthed the word APES and he added. "--not-monkeys."
We'd already established they were not-monkeys in the locker room, Jack scouring himself under the shower and cursing. "Fuckin' filthy fuckin' disgusting fuckin' monkeys!"
And my stock response; "They're not monkeys, Jack. They're apes."
Hence Not-Monkeys has just become Jackspeak for 'apes'.