Green’s Dictionary of Slang

act the (giddy) goat v.

also …silly goat, play the (giddy) goat
[goat n.1 (2); the assumption is that the animal is naturally foolish; note Stephens & O’Brien, Materials for a Dict. of Aus. Slang (ms. 1900–10): ‘No doubt a humorous variation of “caper”.’]

to behave foolishly.

[UK]R. Morton ‘Gay Paree’ [lyrics] Dick began to play the goat – he Chucked his girl beneath the chin! – Called her ‘Yummiest of Totties!’.
[Aus]H. Lawson ‘An Incident at Stiffner’s’ in Roderick (1972) 118: Danny was ‘acting the goat’ round the fireplace.
[UK]W. Pett Ridge Mord Em’ly 251: ‘Stop acting the goat,’ he said brusquely.
[Aus]Bulletin Reciter 1880–1901 79: We reckoned that he’d struck a patch — if none would act the goat.
[UK]Marvel III:54. 4: Get up, and don’t act the giddy goat!
[UK]D. Blackburn Leaven 190: There ain’t many laws [...] a man can’t get over if he’s smart, and don’t play the giddy goat.
[UK]Magnet 27 Aug. 11: It’s a bit thick if Bunter is to score all along the line like this, after acting the goat in that way.
P.C. Wren Dew and Mildew 136: You preferred to play being Grown-Ups, and Grown-Ups don’t act the giddy goat.
[UK]E. Pugh Cockney At Home 190: I’d orate myself, but, as you know, this don’t happen to be my day for actin’ the silly goat.
[Aus]Truth (Melbourne) 10 Jan. 6/3: They were wrestling on the footpath, signing out, and acting the goat.
[NZ]Feilding Star (NZ) 25 Apr. 2/4: He asked me not to play the giddy goat.
[Aus] (?) H. Lawson ‘The Last Rose of Winter’ in Roderick (1972) 910: It served him right for acting the goat.
[UK]Strand Mag. LXIII 125: ’Ere, young fellow, ’op it, and don’t act the giddy goat.
[UK]Chips 12 Sept. 1: Why don’t you act the goat properly, Willie?
[UK]‘Hergé’ Tintin and the Red Sea Sharks 9: Haven’t you finished acting the goat yet?
[UK](con. 1939) J. Rosenthal Evacuees Scene 29: She was listening to Lord Haw-Haw on the wireless yesterday – and said she knows who he really is [...] Jack Buchanan acting the goat!
C. James Poem of the Year 73: We’re told the Queen has carpeted Andrew / And warned him not to act the giddy goat.
[UK]Dandy Comic Library No. 205 50: He’s acting the goat!
[UK]J.J. Connolly Layer Cake 248: You was performing, acting the goat, you was gonna fuckin shoot ’em all.