Though undercover cops recently arrested one pervert, there never seems to be a shortage! Take this terrible story recounted on HollaBack. A reader said that on a D train this morning, between Atlantic-Pacific and Grand, "I was napping with my iPod on, and I woke up because I felt something repeatedly hitting and rubbing up to my arm. When I looked down, I saw an uncircumcised penis being masturbated right on top of my arm. Luckily, he hadn't finished yet. (Though the police mentioned that it would have been better to have DNA evidence. Ew.) I immediately screamed something like 'OH MY GOD, GET OFF OF ME YOU SICK MOTHERFUCKER!' At that point, the man mumbled something like 'sorry' and walked quickly through the crowd to the other side of the train. I was stunned that no one tried to stop him, and even shifted to let him through. I screamed again 'DID ANYONE SEE THAT? THAT ASSHOLE WAS MASTURBATING ON ME!'" (Read the full story here.)The HollaBack reader took the man's photograph while he pretended to be asleep and reported him to the cops, but because he's still at large, a happy, um, ending remains elusive.