Green’s Dictionary of Slang

1. a worthless, contemptible person.

1858		A. Mayhew Paved with Gold 147: A supercilious, high-flown squit, with her ‘please do this,’ and ‘be so kind do that’.
1926		‘Ford Madox Ford’ Man Could Stand Up 113: A half a dozen quite decent if trying young squits.
1937		E. Raymond Marsh 111: You’re not the world’s dirtiest little perishing squit, are you?
1940		M. Marples Public School Slang 59: Boys in general have a great flair for derogatory and vituperative expression [...] swot, swank, sneak, jew, swine, tick, scoff, cad, blog, nip, oik, lout, wet, drip, squit, squirt, mug, scug, sap, simp, seet, gump, muff, goof, goop, waft.
1958		Willans & Searle Complete Molesworth (1985) 384: 5 squits, 9 snekes, 19 cribbers.
1976		C. Dexter Last Seen Wearing in 2nd Inspector Morse Omnibus (1994) 406: Where shall we go, you dirty little squit?
2000		Indep. on Sun. Rev. 6 Feb. 24: Little squits, the ones who want to get you into hot water just for the sake of it.

2. (UK juv.) a short person.

1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 190: Shrimp, small fry, snitch or snitchy, squib, squit (thus also Anstey in 1889, ‘He’s not half a bad little squit’).
1999		N. Cohn Yes We have No 121: A little squit of a man comes in.