A 15-year-old Brooklyn boy was arrested yesterday after accidentally shooting himself in the penis. The Post's stupid headline is, "So much for packing a, um, rod," and there are going to be plenty of bad jokes about going off half-cocked in the comments, but we can't help but pity the kid. Khamir Grant told cops he was walking home from Amersfort Park in East Flatbush around 1:30 a.m. Sunday with a gun in his waistband when the piece began to slip into his pants. When Grant grabbed for it, he accidentally pulled the trigger, firing a bullet "right through his penis," in the Post's words. Grant staggered home, told his mother what happened, and they took a livery car to Kings County Hospital, where Grant was released after treatment and then arrested. He's charged with reckless endangerment and criminal possession of a weapon—the same charges levied against Plaxico Burress, who last year shot himself in a nightclub under similar circumstances, albeit with less catastrophic results.