Matthew Denny, a 17-year-old suburban Caucasian, is recuperating following a harrowing near-def experience Monday at Newton's NorthTowne Mall. 'He came out of Bradlee's wearing a Starter jacket and Tommy Hilfiger sweatshirt, and suddenly he fell down and went into convulsions,' witness Irene Wheeler said. 'Writhing on the floor in those baggy pants, he looked like he was on the verge of def.' Denny was rushed to a local hospital, where doctors administered emergency doses of Matchbox 20's Yourself Or Someone Like You. 