Green’s Dictionary of Slang

plakkies n.

[Du. plakken, to glue; they ‘stick’ to one’s feet]

(S.Afr.) thongs, flip-flops.

[SA] informant in DSAE (1996).
M. Cozien in UCT Studies in Eng. Feb. 29: Beach-thongs, sandles [sic] made of rubber [...] have a great many names here — sloppies, slip-slops, plakkies, etc [DSAE].