Green’s Dictionary of Slang

1. a gun.

1942

R.L. Bellem ‘Malibu Mess’ Dan Turner – Hollywood Detective Dec. 🌐 I jammed myself against him so he could feel the rodney in my duke.

2. the penis.

1967–8		Baker et al. CUSS.
1978		L. Kramer Faggots 320: Dong and schlong and willy and rodney.