Green’s Dictionary of Slang

trim n.

[? SE trim, neat, attractive, pretty]
(orig. US black)

1. [1930s+] a woman’s genitalia; the female pubic hair.

2. [1930s+] (also trimming) a woman, always in a sexual context; thus get some trim

3. [1950s+] cunnilingus.

In phrases

get some trim (v.)

[1980s+] of a man, to seduce, to have sexual intercourse.