The idea came to Pete Melfi, a radio personality turned podcaster in St. Augustine, Fla., last year after he organized “the laziest race in the history of races,” a .5-kilometer beer run, and the participants had a grand old time.Wouldn’t it be fun, Mr. Melfi thought, to hold another race, this time with a big after-party? And what if the theme was none other than the meme that launched many thousands of headlines about his home state: Florida Man?His wild idea morphed into an all-day competition with a series of zany events: A mullet contest. A “mud duel” with pool noodles. An…