Its a apparently meaningless word, created by the Spanish comedian Chiquito de la Calzada that became part of the collective language and recurrent in the Spanish jokes slang. Its a funny world by itself and can be replaced by any meaning. Specially funny when replacing sexual words or when being used to insult somebody in a funny and friendly way
that woman is naked you can see all his his down fistro

that man is touching his sexual fistro

i dont believe your tales you are such a fistro
by musero May 10, 2011
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