Green’s Dictionary of Slang

(S.Afr.) a general excl. of dismay, annoyance, surprise etc; synon. with God!

1919		R.Y. Stormberg With Love from Gwenno 57: She made quite a brilliant ass of herself at the piano [...] bawling away at some ballads which I couldn’t recognise for the badness of their rendition. Martin burst in with ‘Maar gits! you should just hear Miss Davis sing that song! Nobody can sing like wot she ken!’ [DSAE].
1982		Sun. Times (Johannesburg) 21 Mar. 44: He was not happy when the British arrived. ‘Can a person be happy in such a time? Gats! We were in jail!’ [DSAE].
1992		C. Knox trans. in Van Heerdens Mad Dog 68: A commotion broke out at the cage ... ‘He’s caught hold of Jock, oh gattela!’ Tattie looked round guiltily — I’d heard him sneakily egging Jock on to bark at the monkey [DSAE].