Green’s Dictionary of Slang

(S.Afr.) a mixture of marijuana and powdered methaqualone (Mandrax); thus the act of smoking or the pipe used.

1986		cited in J. & W. Branford Dict. S. Afr. Eng. (1991).
1994		D. Reed Beloved Country 146: The witpyp (‘white pipe’) is spectacular to watch. The flame from the match grows huge as the mixture burns in the wide end of the bottle neck.
2004		F.P. Smith Hbk Forensic Drug Analysis 466: In South Africa, methaqualone is usually smoked in a ‘witpyp’ (ie, white pipe) mixed with Cannabis.