Green’s Dictionary of Slang

1. prepared, ready.

1964		H. Selby Jr Last Exit to Brooklyn 141: The President of Local 392 continued [...], explaining that [...] the union was completely ready and geared for the strike.
1971		(con. 1930s) B. Short Black and White Baby 48: My mother was not geared to cope with hard times. A vain and impractical woman in many ways, she didn’t know how to cut corners .
1998		I. Welsh Filth 136: All geared up for the Testimonial?

2. (Scot./US black) dressed up.

1966		F. Elli Riot (1967) 178: Let’s take a hike over there [...] You’ll never get another chance to see a buncha geared-up freaks like that in action.
1973		(con. mid-1960s) J. Patrick Glasgow Gang Observed 232: Geared up – dressed to kill.

3. (US) very (sexually) excited.

1972

B. Rodgers Queens’ Vernacular 109: lusty [...] geared [up].