What is "chimped"

Usage examples of "chimped".

There they were, the Rainbow team, almost all of them looking as if asleep, but probably just chimped down, as he'd done with 3rd SOG more than a generation before, just pretending to sleep, eyes closed and powering their minds and bodies down, because it made no sense to think about things you didn't know jack shit about, and tension sapped the strength even when your muscles were idle.