Green’s Dictionary of Slang

(UK Und.) a scheme to arrange for typewriters and vacuum cleaners to be left on approval at a residence, the goods would then be sold and the premises quickly vacated by the con man and his partner.

2002

(ref. to 1940s–50s) L. Pizzichini Dead Men’s Wages (2003) 106: Charlie could house a string of girlfriends to work the tapper and sucker racket [...] A tapper is a typewriter, and a sucker is a vacuum cleaner. Charlie would go to the tapper shop and tell the manager that his wife was thinking of buying a typewriter [...] the salesman would leave it on approval for ten days.