Green’s Dictionary of Slang

billy-o n.

[-o sfx (7)]

1. (also billyho, billy-ho, billy-oh) euph. for hell, thus trouble, punishment.

[Aus]Bulletin (Sydney) 2 July Red Page/4: ‘O Listen to our tale of woe!’ / The statisticians cry in chorus: / ‘The birth-rate’s gone to Billyho!’.
[UK]Punch 25 May 584/3: He would take a team anywhere... He would take a team to Billy-O .
[Ire]H. Leonard Da (1981) Act I: I got billy-ho for going with you to that fillum.
[Aus]D. Ireland Burn 103: Strike me roan, one word and you’re off the track to billy-oh!
[Aus]R. Beckett Dinkum Aussie Dict. 8: Billy-oh: [...] One’s rheumatism, sciatica or mild case of clap can also be, ‘giving one billy-oh’. One can also give the neighbour’s unpleasant dog billy-oh which translates into the fact that one has beaten the wretched animal half to death with a pick handle.
[Aus]Bug (Aus.) 1 Oct. [Internet] John Howard-Cunningham grabbed the little Hawke ball without blanching and ran to billy-o with it.
[NZ]McGill Reed Dict. of N.Z. Sl. 91: gone to billyo 1. Disappeared, gone to a faraway place, where you boil the billy in the great outdoors. 2. Messed up, plans gone awry, the influence of ‘Old Billy’, the Devil.

2. nonsense, rubbish.

[UK]J. Buchan Thirty-Nine Steps (1930) 40: His talk of Epirote guards that would skin their own grandmothers was all billy-o.

In phrases

like billy-o (adv.) (also like billyho, …billy-ho, ...billy hell, ...billy-oh, ...(the) billyo) [dial., euph. for ‘bloody hell’]

a general intensifier and expression of energy or effort, most enthusiastically, strenuously, speedily.

[UK]Western Times 27 Aug. 8/1: ‘Yes,’ said a bye-stander, a labourer, ’ and I zee’d et too comin’ out like Billy O’.
[UK]Western Times 1 Apr. 7/3: He assured the bench that she was — well not sober; and added, ‘She cumm’d out swearing at I like Billyo!’.
[UK]Referee 9 Aug. 7/4: It’s just a new hat I’ll be afther buying, and it’s my umbrella I’ll be lavin’ at home and shure it’ll rain like billy-ho!
[UK]Sporting Times 27 Jan. 1/2: It used to make me chuckle like sixteen to find my seven [i.e. wives] all sitting up in the hall and quarrelling like billyoh amongst themselves as to their order of precedence in going for me!
[Aus]J. Furphy Such is Life 141: Horf goos ’em ’osses loike billy-o.
[UK]E. Pugh Cockney At Home 87: She’s so full o’ fun. So witty. She made me laugh like billy-oh.
[NZ]‘Anzac’ On the Anzac Trail 54: [T]he women [...] seem quite content to graft away like billy-oh, while their owners lie in the shade and smoke.
[UK]Wodehouse Damsel in Distress (1961) 93: ‘Pigs squeal like billy-o, m’lady!’ he observed [...] ‘Oo! ’Ear ’em a mile orf, you can!’.
[UK]D.L. Sayers Unpleasantness at the Bellona Club (1977) 77: Works like billy-o to keep the home together and all that.
[UK]J.B. Priestley Good Companions 605: There they are, falling in love all over again like billy-oh.
[US]J. Conroy Disinherited 273: This will hurt like billy hell.
[UK]D.L. Sayers Nine Tailors (1984) 110: On the day of the funeral it rained like billy-oh!
[Ire]‘Flann O’Brien’ At Swim-Two-Birds 80: The whole place was burning like billyo in no time.
[UK]Wodehouse Mating Season 249: I quailed, as a matter of fact, like billy-o.
[Aus]D. Niland Shiralee 122: I wanted like billy-o to shake him off, but I didn’t know how.
[US]N.B. Harvey Any Old Dollars, Mister? 107: I got annoyed, because it tickled like billy-o.
[UK]C. Wood Fill the Stage With Happy Hours (1967) Act VI: He’s tried like billyho to get us a council grant.
[Ire]H. Leonard Time Was (1981) Act II: The beggars are running like billy-o. Hurrah!
[Aus]R. Beckett Dinkum Aussie Dict. 8: Billy-oh: A somewhat archaic word that can either mean that one has had a wonderful time at a party or that one is feeling more than slightly off-colour or sick; thus, ‘I played up like billy-oh last night,’ or, ‘my rheumatism is playing up like billy-oh.’.
[UK]K. Lette Llama Parlour 151: I should have got out of the stretch limo and run like the billyo, the minute we got to the mansion.
[UK]A. Warner Sopranos 47: ‘Can you feel your baby kick at all?’ [...] ‘The wee thing starts booting away like billy-oh’.
[UK]Guardian Rev. 10 Mar. 2: I shall force my way to the front of the upper deck in the hope of catching Sir P swearing away like billyo.
[UK]T. Black Artefacts of the Dead [ebook] He was screaming like billy-o.