Porn star accused of exposing himself and masturbating on a NYC subway gets off -- on a technicality.

Five times last year, porn actor and registered sex offender Kenneth Hoyt allegedly exposed himself and started masturbating on Manhattan subways - once in front of two 16-year-old girls.

But the whole bundle of misdemeanor charges - including seven counts of public lewdness, one count of indecent exposure and two counts of endangering the welfare of a child - were dismissed by a criminal court judge last week.

The reason? Prosecutors with the Manhattan District Attorney's Office missed the legal deadline for bringing the Hell's Kitchen perv to trial in a timely manner - by only four days. » Article here