Green’s Dictionary of Slang

(S.Afr.) a bite, a mouthful, a morsel.

1970		informant in DSAE.
1984		Frontline Feb. 33: There had been a peach on the back seat [...] One grabs it, takes a hap, and it quickly does the rounds [DSAE].
1996		CyberBraai Lex. at www.matriots.com 🌐 Hap. Pronounced ‘ghup’, this means ‘bite’ and is used in the following fashion: ‘Give me a hap of your apple. Ag, please’.