Green’s Dictionary of Slang

mini-mini n.

also minny-minny
[Lat. minimus, smallest, but note Twi mini-mínã, a small, stinging fly + Hausa míni, smallness]

(W.I.) small spots that one sees in front of one’s eyes, either as a result of a blow to the head, or from the mild hallucinations that may accompany the smoking of ‘ganja’.

[WI]cited in Cassidy & LePage Dict. Jam. Eng. (1980).