Green’s Dictionary of Slang

1. to take by surprise.

[1906		J.W. Carr ‘Words from Northwest Arkansas’ in DN III:ii 127: blind side, n. phr. In the expression, ‘to get on the blind side of,’ which means ‘to take by surprise’].
1956		CQ Congressional Qly Wkly Report 551/3: O’Neill claimed he was ‘blind- sided’ by the Agriculture Committee's , decision to report the bill.
1970		W. Goldman Father’s Day 95: Amos' quirky mind, [...] was in no way ready for that song, and as its power blindsided him, back he tumbled where he never much wandered any more, into his frigid Illinois boyhood.
1981		J. Wambaugh Glitter Dome 173: She had blindsided him with that kiss. It was the last thing he expected.
1997		E. Little Another Day in Paradise 70: This cat’s partner blindsides him.
2000		F. Kellerman Stalker (2001) 374: Hayley, at least it would have put me on the alert. This way, I was totally blindsided.
2001		(con. 1975–6) E. Little Steel Toes 52: Monkey blindsides Big George with a piece of pipe.
2010		H.A. Sexton Altared Ego 249: That punk had blindsided him and hit him from behind with num-chucks.
2011		N.J. Walters Touch of Magick 95: Rhiannon's confession had blindsided him. The last thing he’d expected to discover was that [...] she was a witch.
2017		V. McDermid Insidious Intent (2018) 241: ‘I don’t want Carol to be blindsided by more misunderstanding’.
2019		S.M. Jones Lives Laid Away [ebook] ‘He called a couple of district representatives, who blindsided the commissioner’.
2020		(con. 1991-94) W. Boyle City of Margins 79: She wonders if she should call Alberto to tell him [...] so she doesn’t blindside him over dinner.
2021		C. Hammer Opal Country 196: Blindsided. Some arsehole crept up from behind and laid waste to him.

2. to take advantage of.

[1826		C.M. Westmacott Eng. Spy II 397: The Bristol men ‘down along,’ sleep, they say, in this way and hence is it rare for Jew or Gentile, Turk or infidel, to get the blind side of them. Some of them, however, have ere now been done brown].
1985		J. Wambaugh Secrets of Harry Bright (1986) 100: Make her promise first! She’ll blind-side me, the sneaky bitch!
2001		(con. 1929) N. Tosches Where Dead Voices Gather (ms.) 137: Brown talks of blindsiding his woman, of [...] ‘spendin’ her jack’.