Green’s Dictionary of Slang

stop n.3

[Afk. stop, a plug or fill of tobacco]
(S.Afr. drugs)

1. (also stops) marijuana.

Drum (Johannesburg) Sept. 12: Derived from Hottentot Dachab, it [i.e. dagga] is known in the slang as ‘ganja,’ [...] ‘stops,’ ‘boom,’ (etc.) [DSAE].
Drum (Johannesburg) 27 Aug. 7: He pauses to recall the pleasant moments of his most recent encounter with ‘stop’. ‘You know, I’m seriously thinking of giving up the booze and hitting the weed full-time’ ... Aardpyp (earth-pipe): Four to six foot length of steel tubing with the stop packed in at one end; you pull while lying flat on your stomach [DSAE].
[SA]Sun. Times (Johannesburg) 1 May 7: They are regular dagga smokers and know a number of places to buy ‘stop’ [DSAE].
L. & P. Robertson-Hotz in Bloody Horse No.3 36: Nearby there was a span of stop, I remember, fields of the stuff [...] We just perch there, smoke some stop, slap away mosquitos [DSAE].
[SA]P. Hotz Muzukuru 3: They’d stocked up with a couple of crates of beer and a kilo of grade one stop.

2. (also stopper, stoppie) a single pipeful of marijuana or enough to roll a single cigarette; such a quantity is the smallest amount sold; cit. 1946 refers to a marijuana cigarette itself.

[SA]H.C. Bosman Cold Stone Jug (1981) II 23: The Bombardier takes a piece of paper [...] and tears it into the right size and then pulls out some of the old queer and mixes some cigarette tobacco with it, and in a few minutes we are sitting as happy as you please [...] pulling away at that dagga-stoppie.
[SA]A. La Guma Walk in the Night (1968) 32: I should’ve bummed a stop off them. I feel like a stop.
Eng. Usage in Southern Afr. V:1 11: To the ordinary smoker a stop (Afrikaans pronunciation) means a fill for a pipe or sufficient [...] to roll a skuif: to the roker, stop means boom-stop. These stops — or rather the boom for the stop [...] come in varying parcels [DSAE].
[SA]P. Slabolepszy Sat. Night at Palace (1985) 69: Hey, what’s this? Stopper? You a bloody rooker, chief? Gott, there’s enough boom here to — [...] How much you make on the quiet, chief?