Navy, n. — Green’s Dictionary of Slang

Navy n.

[Navy Cut, a brand of tobacco]

a cigar or cigarette end left burning on the pavement.

1926

N. Klein ‘Hobo Lingo’ in AS I:12 652: Navy—cigar end or ‘butts’ found on side-walk.

Navy cake (n.) [cake boy under cake n.¹]

(US gay) a male homosexual sailor.

1972		B. Rodgers Queens’ Vernacular 22: If the sailor is gay, he is [...] a piece of Navy cake.
1989–2003		R.O. Scott Gay Sl. Dict. 🌐 a piece of Navy cake: a gay sailor amenable to homosexual sex.

Navy office (n.) [pun on fleet/Fleet; the prison name refers to the Fleet River, itself f. OE fléot, a tidal inlet]

the Fleet Prison.

1823