Rising hip hop star DJ Megatron was shot dead yesterday while walking to a Staten Island store to buy a cheap cigar. "It's earth-shattering," says his mom. "He was our golden child." Megatron, whose real name was Corey McGriff, got his start on local Hot 97 radio and was a regular on BET's 106 & Park. A former friend had bashed the 32-year-old hip hopper in postings linked to Megatron's YouTube videos, apparently over an unpaid debt. "Bad s--- will continue happening to u, Dude!" said one posting, reports the New York Daily News. Police are still seeking a motive.