Green’s Dictionary of Slang
[late 18C–19C] (US Und.) a crowbar.
SE in slang uses
[the Oxford version of Cambridge’s fellow commoner n.; commoners, as opposed to scholars, were seen as empty-headed]
[late 18C–early 19C] (orig. Oxford Univ.) an empty bottle.gentleman-outer
[early 18C] a highwayman.gentleman-usher
[? pun on SE gentleman usher of the Black Rod; note Williams: ‘gentleman usher [...] a male attendant on a lady, sometimes providing a sexual or pimping service’]
[late 16C–early 18C] the penis; .
[17C] a woman’s male companion.
do the gentleman
gentleman in blue (and white)
(also gent in blue) [the uniform]
[mid–late 19C] a policeman.gentleman in brown
gentleman in red
gentleman wants to take a chance
[1910s] (US short-rder) a plate of hash.gentleman who pays the rent
[late 19C] (Irish) a pig.