Green’s Dictionary of Slang

1. (US) to act as an informer (against); thus stooling n. and adj.

1900		A.H. Lewis ‘The Garrote’ in Sandburrs 136: D’ Face’s pal, Spot, gets too gabby wit’ a skirt, who’s stoolin’ for d’ p’lice on d’ sly.
1915		G. Bronson-Howard God’s Man 129: Too many dicks stooling for the D.A.
1927		(con. 1917) J. Stevens Mattock 233: They [...] had been brung up to think that what they called stooling was a crime.
1929		A.J. Barr Let Tomorrow Come 238: You’re the rat stooled on old man Kennedy.
1931		C. Martinez ‘Gats in the Hat’ in Gun Molls Sept. 🌐 What you doing then: Stooling for the Flatties?
1938		R. Chandler ‘Red Wind’ in Red Wind (1946) 28: Stooled on a bank job in Michigan and got me four years.
1947		B. Schulberg Harder They Fall (1971) 255: He’s got you stooling for him like the rest of his mob.
1949		I. Shulman Cry Tough! 17: A stooling cop. My sister going with a cop!
1955		B. Schulberg On the Waterfront (1964) 146: It’s stoolin’ [...] Don’t you see? I’d just be stoolin’ for you.
1959		W. Brown Teen-Age Mafia 133: Goldblatt ain’t going to stool on us kid. He’s a fence.
1965		C. Himes Cotton Comes to Harlem (1967) 22: Here’s a rat who stooled on his former policy racketeer bosses.
1975		E. Torres Carlito’s Way 72: I say he’s stooling for Interpol.
1989		(con. 1950s) Courtwright & Des Jarlais Addicts Who Survived 194: I stopped selling because too many stool pigeons started stoolin’.

2. (US Und.) to search premises for drugs.

1920

F. Williams Hop-Heads 27: The ‘dicks’ are always ‘stooling’ around. You can never tell when they are liable to walk in.