Green’s Dictionary of Slang

bar v.1

[? 17C bar, to take exception to + dicing and two-up jargon bar, to declare a throw void]

1. (also bar out) of actions, to reject unequivocally.

[UK]‘Peter Pindar’ ‘Peep at the Academy’ Works V (1812) 355: They call thee a fine China jar: But this I humbly beg to bar; They should have said a pipkin of brown crockery pot.
[US]D. Crockett Col. Crockett’s Tour to North and Down East 104: We may as well dismiss ourselves, and go home; shut up shop, bar out the schoolmaster, and save the expense of a Congress.
[UK]Swell’s Night Guide 110/2: Bar that, cheese it, cut it, leave off.
[US] ‘Scene in a London Flash-Panny’ Matsell Vocabulum 100: ‘Bar that toss, Jim,’ said Bell, ‘for you’re as fly at the pictures, as the devil at lying.’.
[UK]Sporting Times 22 May 1/3: He seized her and said, ‘I bar squeaking’. ‘Bar the door you fool’, was the prompt reply.
[UK]‘Pot’ & ‘Swears’ Scarlet City 180: Bar chaff. [...] What do they do?
[US]S. Lewis Kingsblood Royal (2001) 108: He would not jimcrow it and bar out Negro customers.
[Aus](con. 1941) R. Beilby Gunner 299: ‘Barred,’ shouted the ringie [...] ‘Bar that spin! All bets stand!’.
8Ball & MJG ‘Miggaz Like Us’ 🎵 Let these bastards know that we don’t bar no fuckin’ blood stains.

2. (Aus.) of people, to dislike intensely.

[Aus]Aussie (France) 12 Mar. 1/2: You can Promenade avec the Gal and her Father if you like, but We bar Petit Garcons and Filles.

3. (US black) to back down, e.g. from a fight.

Fat Pat ‘Why You Peepin Me’ 🎵 You know we don’t bar.

In exclamations

SE in slang uses

In phrases

bar the bubble (v.) [SE bar, except + play on bubble n.1 (2)]

to make an exception against the general rule.

[UK]Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: To bar the bubble. that is to except agreement [of] that General Rule, that he who lays the Odds must always be adjudged the loser. This is particularly restricted to bets laid for Drink.
[UK]Grose Classical Dict. of the Vulgar Tongue (2nd, 3rd edn) n.p.: To Bar the Bubble. To except against the general rule, that he who lays the odds must always be adjudged the loser: this is restricted to betts laid for liquor.
[UK] ‘Modern Dict.’ in Sporting Mag. May XVIII 98/2: [as cit. 1788].
[UK]Lex. Balatronicum.
[UK]‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 18: ‘To bar the bubble,’ — to restrict the decision of a bet to the rules of common sense.