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Black flies are a Canadian made Cooler. East coast girls love them and refer to the drunk the get from them as "black fly black out ". Its very rare to hear of a girl who drank four of them to not be black out by the end of the night. Girls Love these coolers because they taste good but are not sugary, there for the do not cause bad hangovers.
" what are you drinking tonight? "-girl 1

" black flies"- girl 2

" Black fly Blackout!!"- girls
by Scotiangirl October 13, 2013