alibi, n. — Green’s Dictionary of Slang

alibi n.

[weakened form of SE]

an excuse.

1912		Collier’s 20 Apr. 15/2: ‘Getting your alibi ready?’ asked Zeider [OED].
1922		W.T. Tilden Lawn Tennis 1: Don’t offer alibis for losing [OED].
1925		R. Lardner ‘Zone of Quiet’ in Coll. Short Stories (1941) 67: A girl’s a fool to marry a doctor. They’ve got too many alibis.
1936		W. Holtby South Riding (1988) 248: Pip’s devotion gave her, she considered, a complete alibi in all charges of frustration and virginity.
1949		C. Hare When the Wind Blows 181: Tom and Maureen are my alibis .
1951		L.P. Hartley Fellow Devils 216: Low spirits make you seem complaining [...] I have an alibi because I’m going to have a baby; but I wonder if Column minds me being so dull.
1960		J. Brosnan Long Season 132: ‘Other pitchers make mistakes and he’s got a million alibis. No excuses where you’re concerned, though. No, sir!’.

In compounds

alibi store (n.)

(US) in carnivals, any sideshow in which the losing punter told why they didn’t win, and given the (paid-for) chance to try (and lose) again.

2012

W. Keyser ‘Carny Lingo’ in http://goodmagic.com 🌐 Alibi Store — A game in which the agent gives you an explanation of why you didn't win [...] He often offers you a ‘better’ chance to win (for another fee, of course) but you'll never win a thing.