Green’s Dictionary of Slang

1. excrement, an act of defecation [shit n.].

1960		A. Buzo Front Room Boys Scene i: Then he raced out to the john for an Edgar Britt.
1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 110: With all them coppers chasing me I nearly done an Edgar Britt in me strides.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 13: In the naval fleet of a thousand halfsoles, / neath Tilly Devine of the swinging brace and bit / there lived a chow sheila by the name of Hoo Flung Edgar.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Edgar Britt. Excrement. Rhyming slang for shit. Sometimes just Edgar.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 64/2: Edna Brit n. shit.
2004		R.G. Barrett Rosa Marie’s Baby (2013) [ebook] ‘I’m going for an Edgar’.

2. in pl. diarrhoea [shits, the n. (1)].

1989		J. Hughes Aus. Words 188: You give me the Edgar Britts, sometimes.
1989		R.G. Barratt ‘So Why Doesn’t Jack the Lad Get a Real Job?’ in What Do You Reckon (1997) [ebook] They get the Edgar Britts and want to fight you.