A word of greeting amongst typically, but not exclusively, male Chavs, Townies and Scally's. Derived from the mispronunciation of the word 'boy', it is often used multiple times in the same sentence. It is most commonly used in a friendly manner, although when the enevitable eruption of tension and/or violence occurs between members of the community(ies) to which it belongs, it will be replaced, ironically, with the word 'mate'.
Male 1: "Alright buy? What's 'appnin buy?"
Male 2: "'ere buy did you see the buy other day what smashed that window down KFC in town?"
Male 1: "fuckin' 'ell buy yeh what a nutter innit buy!"
Male 2: "Yeh I know buy. Fuckin' gonna smash the cunt's 'ead in buy my fuckin' sister was fuckin' workin in there at the time wunnit buy. And she's fuckin' pregnant!"
(cycle down to next estate on BMX bikes)
Male 2 to Male 3: "Oi mate! You fuckin' smashed that window down KFC mate my fuckin' sister was workin in there and you nearly killed 'er fuckin baby. You're fuckin dead mate!"
Male 2: "'ere buy did you see the buy other day what smashed that window down KFC in town?"
Male 1: "fuckin' 'ell buy yeh what a nutter innit buy!"
Male 2: "Yeh I know buy. Fuckin' gonna smash the cunt's 'ead in buy my fuckin' sister was fuckin' workin in there at the time wunnit buy. And she's fuckin' pregnant!"
(cycle down to next estate on BMX bikes)
Male 2 to Male 3: "Oi mate! You fuckin' smashed that window down KFC mate my fuckin' sister was workin in there and you nearly killed 'er fuckin baby. You're fuckin dead mate!"
by sd999 February 11, 2014
Get the Buymug. When something's REALLY important. The tags "bold," "underline," and "italicize" begin with the letters BUI, hence the term. When someone using BBCode BUIs something, you know shit's about to go down.
by MegamanTTEX November 3, 2010
Get the BUImug. 
by Wolfpack69 March 5, 2009
Get the Buied mug. by Joe Ernster esq. August 6, 2007
Get the buimug.