Green’s Dictionary of Slang

dime v.1

[drop a dime under dime n.]

1. (US) vtr. to pass on information.

[US]Arizona Dly Star (Tucson, AZ) Youth Beat 26 Dec. 8/3: Dime: To inform, to squeal, to rat.
[US]A. Vachss Hard Candy (1990) 138: They won’t dime you for the Sutton Place thing. It won’t fly.
[US]Simon & Price ‘Moral Midgetry’ Wire ser. 3 ep. 8 [TV script] Somebody should dime the brass about this thing.
[US]D. Winslow The Force [ebook] ‘Who dimed me?’.

2. (US und.) vi. to inform against.

[US]L. Berney Whiplash River [ebook] The old Kriol man who’d dimed them to Baby Jesus.

In phrases

dime (someone) out (v.)

(US) to inform against.

[US]N.C. Heard When Shadows Fall 10: ‘Ah laid this dynamite melon to the dude [...] And do you know that the nigga dimed me out to my ole man?’.
P. Blauner Casino Moon 236: ‘I don’t know, man. All I know’s I didn’t have anything to do with it. Maybe your old lady dimed you out. I just know it’s not my concern’ .
[US]L. Berney Gutshot Straight [ebook] ‘I wonder why do you not make plea bargain?’ Shake shrugged. ‘Dime out the most dangerous lady on the West Coast?’.
[US]D. Winslow The Force [ebook] I wish he’d fucking shared it with me, Malone thinks. Given me a word [...] dimed me out, ratted on me to myself.