Green’s Dictionary of Slang

act the (giddy) goat v.

to behave foolishly.

1841		Addr. to Citizens of Philadelphia Establishing Asylum 9: He's in a silly weeping or at playing the goat.
1877		H. Hartigan Stray Leaves (1st ser.) 175: Let me go and ‘act the goat’ (another slang term for playing monkey tricks).
1879		H. Hartigan Stray Leaves 21: Don't be actin' the goat like ould Larry Healey!
1891		R. Morton ‘Gay Paree’ 🎵 Dick began to play the goat – he Chucked his girl beneath the chin! – Called her ‘Yummiest of Totties!’.
1893		H. Lawson ‘An Incident at Stiffner’s’ in Roderick (1972) 118: Danny was ‘acting the goat’ round the fireplace.
1898		W. Pett Ridge Mord Em’ly 251: ‘Stop acting the goat,’ he said brusquely.
1902		Bulletin Reciter 1880–1901 79: We reckoned that he’d struck a patch — if none would act the goat.
1905		Marvel III:54. 4: Get up, and don’t act the giddy goat!
1908		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.
1910		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.
1912		P.C. Wren Dew and Mildew 136: You preferred to play being Grown-Ups, and Grown-Ups don’t act the giddy goat.
1914		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.
1914		Truth (Melbourne) 10 Jan. 6/3: They were wrestling on the footpath, signing out, and acting the goat.
1918		Feilding Star (NZ) 25 Apr. 2/4: He asked me not to play the giddy goat.
1921–2		(?) H. Lawson ‘The Last Rose of Winter’ in Roderick (1972) 910: It served him right for acting the goat.
1922		Strand Mag. LXIII 125: ’Ere, young fellow, ’op it, and don’t act the giddy goat.
1930		N. Lindsay Redheap (1965) 17: ‘I’m not responsible if those chaps act the goat, am I?’.
1953		Chips 12 Sept. 1: Why don’t you act the goat properly, Willie?
1960		‘Hergé’ Tintin and the Red Sea Sharks 9: Haven’t you finished acting the goat yet?
1975		(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!
1983		C. James Poem of the Year 73: We’re told the Queen has carpeted Andrew / And warned him not to act the giddy goat.
1991		Dandy Comic Library No. 205 50: He’s acting the goat!
2000		J.J. Connolly Layer Cake 248: You was performing, acting the goat, you was gonna fuckin shoot ’em all.