Green’s Dictionary of Slang

gaycat v.1

also geycat
[gaycat n.]

(US Und.) to act as a spy for a criminal gang.

[US]A. Stringer Door of Dread 60: How d’yuh know he ain’t gay-cattin’ for Keudell right along?
[US]P. & T. Casey Gay-cat 204: A lazy, easy life wot beats [...] gay-cattin’ for a bunch o’ circus sharpers!