Green’s Dictionary of Slang

panties n.

1. pantaloons.

[US]W.E. Burton Waggeries and Vagaries 95: I’ve a Colt’s revolver in each pantey’s pocket.

2. (US prison) abbreviated underwear worn by a prison homosexual; also in general homosexual use.

[US]C. Shafer ‘Catheads [...] and Cho-Cho Sticks’ in Abernethy Bounty of Texas (1990) 211: panties, n. – men’s brief underwear.
[US]B. Rodgers Queens’ Vernacular 146: panties 1. (camp) underbriefs 2. (camp) trousers.
[US]R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].

In phrases