o Dash Snow is a reference to Dash Snow an American artist from New York. According to a dude who edited wikipedia, "his photos depict scenes of a sex, drug taking, violence and art-world pretense with candor, documenting the decadent lifestyle of a group of young New York City artists and their social circle". In some instances, he used his own semen as a drip method onto photos and his art making it more controversial.
To Dash Snow is to get extremely fucked up have a wild and rambunctious night and have a male or female do a line/ bump of an illegal substance off of another man's penis. It is a reference to one of Dash Snow's famous yet controversial photograph.
I dash snow a shit-load of coke off that other guy's cock.
That girl just dashsnowed two lines off a huge cock.