Green’s Dictionary of Slang

1. a poke into the genital area with a finger or some form of implement.

1938		‘Justinian’ Amer. Sexualis 28: Goose, v. To prod or jerk one’s thumb in between another’s buttocks in an unexpected and vulgar manner. n. The act described above.
1943		H.A. Smith Life in a Putty Knife Factory (1948) 189: Then with tender and loving care he administered a masterpiece – a goose that had finesse to it; not too forceful, not too delicate.
1953		C. Brossard Bold Saboteurs (1971) 156: The fag [...] paid the bill and gave the waitress a sudden goose for an extra tip.
1967		P. Thomas Down These Mean Streets (1970) 131: I pulled the covers off my amigo and gave the lifelike corpse a mighty goose and it came to outraged life.
1973		(con. 1940s–60s) Hogbotel & ffuckes ‘The Ballad of Dan Homer’ in Snatches and Lays 18: An’ she went for a tickle and got the whole goose.
1976		R. Price Blood Brothers 31: Stony cautiously lifted the wax applicator between the guy’s legs and gave him a stiff goose.
1992		S. King Gerald’s Game (1993) 195: It’s just a goose, that’s all it is, Jessie.

2. anal intercourse.

1941

in G. Legman Limerick (1953) 106: There was a young lady named Spruce / Whose favorite thrill was a goose.