Green’s Dictionary of Slang

1. a trickster.

1889		Dead Bird (Sydney) 27 July 7/1: [of a ‘welshing’ bookmaker] The spoofer’s clerk stooped and fitted Jack a couple of times.
1905		Truth (London) 9 Feb. 358/1: In the dictionary of slang there are the words ‘spoofer’ and ‘rotter’—in other words, a man who is a cross between the man who bluffs and the practical joker.
1911		Gem 16 Sept. 11: King John was an awful old spoofer.
1926		Judge (NY) 91 July-Dec. 31: Kibetzer - A wise guy; a spoofer.
1937–84		Partridge DSUE (1984) 1130/2: from ca. 1910.
1961		‘Frank Richards’ Billy Bunter at Butlins 98: We can’t! [...] And you least of all, you fat spoofer.
1986		R.G. Barrett Godson 57: ‘[T]his spoofer, all dressed in black with a ridiculous black hat on and some stupid medallion strung round his neck comes up [...] and demands an interview’.
1993		R. Doyle Paddy Clarke Ha Ha Ha 271: He was a sap, a spoofer and a liar.
2003		Brummagem Dict. 🌐 : spoofer n. a person who makes things up; a teller of tall tales [...] ‘You’re a right spoofer, you are.’.

2. (UK Und.) a trick, a hoax.