Green’s Dictionary of Slang

(orig. US milit.) camouflage (uniform).

1972		R. Glasser 365 Days 239: ‘Hey you ... you in the camies.’ ‘Camies ...!’.
1986		R.G. Barrett Godson 184: ‘I’ll give you bloody manservant [...] ,’ growled Norton, draping his cammies over a chair.
1986		L. Heinemann Paco’s Story (1987) 157: Or they can park and stand real close (dressed in their K-Mart cammies), and get a lump in their throats.
1992		S. McCrumb Hangman’s Beautiful Daughter 205: LeDonne was picturing himself in camos, crawling through the wet woods, reactivating senses he hadn’t needed for twenty years .
1992		R.G. Barrett White Shoes 150: They were all dressed in full desert cammies and carrying machine guns.
1997		C. Hiaasen Lucky You 29: You need some camos, buddy.
2020		D. Winslow ‘The Last Ride’ in Broken 286: ‘You dumbass cammies and your ARs’.