Green’s Dictionary of Slang

he n.

also him
[the dating is almost random, as Partridge says, this personification is ‘prob. almost immemorial’]

1. the penis.

[UK]Nashe Choise of Valentines (1899) 12: I kisse, I clap, I feele, I view at will, Yett dead he lyes, not thinking good or ill.
[Ire](con. 1940s) B. Behan Borstal Boy 168: You want to shove ’im under the coldwater tap.
[US]Maledicta IV:2 (Winter) 189: The reverse process of this [...] depersonification of the penis is its personification [...] as little man, foreman, him.
[UK]P. Barker Blow Your House Down 26: ‘I’m afraid he’s not quite ready,’ he said.

2. (US gay, also he-bitch) used by lesbians in the same way as male homosexuals refer to each other as ‘she’.

[US]T.I. Rubin In the Life 68: This here lousy, goddam stud clobbered me [...] The dirty, lousy he-bitch!
[US]Guild Dict. Homosexual Terms 41: she (pron.): One of the several pronouns used by effeminate homosexuals of themselves and their friends. The reverse he is true of lesbians.
[US]C. Fletcher Pure Cop 106: Gumps are also known as ‘he/she’s’. But actually, in their terminology, they’re queens. And their code is ‘We special girls’.