Before there was Sean Kingston or Sean Paul, there was Shaggy: dancehall reggae’s original poster child. The Grammy-winning Jamaican artist, now 41, took dancehall crossover to unprecedented heights, first with 1995′s platinum Boombastic album and then again in 2001 with the six-times-platinum Hotshot, which featured dancehall’s first Number One pop single. This year, in time for the beach comes his seventh release: Summer in Kingston (available digitally now). To celebrate it, Mr. Boombastic closed down the streets of Kingston, Jamaica, for a massive free block party last Saturday, performing alongside dancehall artists Bounty Killer and Elephant Man. Backstage, he spoke with Rolling Stone about breaking records, joining the Marines and making dancehall go pop.