He certainly had a July 4 weekend to recount to his school friends. Sean “Diddy” Combs’ White Parties in the Hamptons were not typically child-friendly—a fact that Justin Litovsky, now 30, discovered as a young 6-year-old with well-connected parents.

Justin and his parents attended what they thought was a Diddy-hosted “afternoon barbecue” on July 3, 1999, only to find…