Green’s Dictionary of Slang

1. (also godfather-in-law) a juryman.

1596		Shakespeare Merchant of Venice IV i: In christning thou shalt haue two godfathers, Had I been iudge, thou shouldst haue had ten more, To bring thee to the gallowes, not to the font.
1616		Jonson Devil is an Ass V iii: If you be such a one, sir, I will leave you, To your godfathers in law: Let twelve men work.
1630		T. Randolph Muses’ Looking-Glass IV iv: I had rather zee him remitted to the jayle, and haue his twelue God-vathers, good men and true, contemne him to the Gallowes.
1785		Grose Classical Dict. of the Vulgar Tongue n.p.: godfathers, a jury; to take the opinions of one’s godfathers, to be tried before a jury.
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Jurymen are also called Godfathers, because they name the Crime the prisoner before them has been guilty of, whether Felony, Petty Larceny, &c.
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn).
1811		Lex. Balatronicum [as cit. 1796].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1859		Matsell Vocabulum 38: godfathers Jurymen; so called because they name the degrees of crime as to grand or petit larceny, etc, etc.
1864, 1867, 1870		Hotten Sl. Dict.
1873		Sl. Dict. 331: Twelve godfathers a jury, because they give a name to the crime the prisoner before them has been guilty of, whether murder or man-slaughter, felony or misdemeanor. Consequently it is a vulgar taunt to say, ‘You will be christened by TWELVE GODFATHERS some day before long.’.
1881		Trumble Sl. Dict. (1890).
1895		Herald (Melbourne) 27 Aug. 2/8: But they chose to go before his nibs, and the twelve godfathers (jury). As they had a ‘prior’ or two against them they were sent on the station for three years.

2. one who pays the bill after a meal or a session of drinking.

c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Godfather. He who pays the Reckoning, or answers for the rest of the Company: as, Will you stand Godfather, & we will take care of the Brat; i.e. repay you another time.
1788, 1796		Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn).
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.