Green’s Dictionary of Slang

(orig. US) a sample of something to arouse or whet one’s appetite, a taste; also as adj.

1837		‘Sambo’s Black Pudding’ in Icky-Wickey Songster 34: The black [...] held in his hand his black towser. / The lady looked at it with joy, / For she never had seen such a teazer.
1903		‘Hugh McHugh’ I Need The Money 80: ‘I’m layin’ a small amount on Beans,’ I went on, as a teaser.
1935		C.G. Finney Circus of Dr Lao 19: This is only a teaser to the main dish.
1965		H.S. Thompson letter 18 April in Proud Highway (1997) 505: The headline technique is called a ‘teaser.’.
1989		M. Amis London Fields 423: On the eve of Bonfire Night, of Final Night, a couple of hours before the TV teaser – Keith’s docu-drama – was about to be screened.
1999		Guardian Rev. 29 Oct. 10: They’re now running mop-up teaser trailers in the US.
2001		I. Rankin Falls 314: You might let drop a hint or a teaser, just to show them you’re in the know.
2014		D.B. Flowers Bangs 277: [A]nother quarter-gram package in his pocket as a teaser for Tommy.