Green’s Dictionary of Slang

acorn n.2

[supposed resemblance]

1. (US) the head.

[US]Ade Hand-made Fables 45: He got it into the Acorn that each Tract of Ground [...] was operated as a Gift Enterprise.

2. (US gay, also acorn-top) the glans penis.

Horn Book 136: His weapon thus pressed between the bubbies [...] is deliciously stimulated and soon a superb jet of seed spurts from the dark red swelling acorn, bespattering the neck and face of the woman [ibid.] 46: It now suffices to squeeze the balls at the proper moment to make the liquid spurt out by the hole in the acorn-top [Simes:DLSS].
[US]B. Rodgers Queens’ Vernacular 104: glans penis; the acorn-like bulb forming the uppermost end of the penis [...] acorn.
[UK]J. McDonald Dict. of Obscenity etc.

3. the prostate.

Simes Dict. Lang. Sex & Sexuality.

4. in pl., the testicles.

[US]J. Wambaugh Choirboys 220: [He] shrieked as the spray hit him in the acorns [Simes:DLSS].

SE in slang uses

In compounds

acorn boy (n.)

(US) a thimble-rigger n. (1), operating a fixed ‘game of chance’ in which an acorn is secreted under one of three upturned cups, the cups are switched around by the operator and the players bet on which one is the container.

[US]Whip & Satirist of NY & Brooklyn (NY) 16 July n.p.: There was the ‘thimble rigger’ in all his glory [...] the brother of an ex-justice was there and one of the ‘acorn boys’ cocked his leg for him.
acorn calf (n.) [Western US belief that a cow that ate too many acorns produced weak offspring]

1. (US) of humans and animals, a runt, a weakling.

[US]in DARE.
[US]Weseen Dict. Amer. Sl.
[US]Randolph & Wilson Down in the Holler 222: acorn calf: n. A runt, a poor specimen, a weakling. Applied to human beings as well as to cattle.

2. (US gay, west) an effeminate or homosexual man.

J. Nevins ‘‘Western frontier gay slang’ on Twitter 2 Mar. 🌐 ‘acorn calf’ [...] a cowboy perceived as femme.
acorn-cracker (n.) [such individuals allegedly eat acorns but note cracker n.3 (1)]

1. (US) an uncouth rural person.

[US]J.W. Carr ‘Words from Northwest Arkansas’ in DN III:i 68: acorn-cracker, n. Uncouth countryman.
[US]Berrey & Van den Bark Amer. Thes. Sl. §391.3: Rustic; Bumpkin, Acorn cracker.

2. attrib. use of sense 1.

film review at www.imdb.com 🌐 The acorn-cracker Humour on the one side balance [sic] with the hard life-deal of breezy Villagers on the second side.