Green’s Dictionary of Slang

fellow commoner n.

an empty bottle.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Fellow commoner, an empty bottle, so called at the University of Cambridge, where fellow commoners are not in general considered as over full of learning; at Oxford an empty bottle is called a gentleman commoner for the same reason.
1794		Gent.’s Mag. 1084: One [student at Cambridge] was a Harry Soph; another a fellow-commoner and senior Soph, and occasionally jocularly called an empty bottle, whilst e contra, a bottle decanted was, from time to time, denominated a fellow-commoner.
1811		Lex. Balatronicum [as cit. 1785].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict.