JOEY FATONE waltzed into an LA post office and was rushed by three femme fans who pleaded for a preview of hot moves he’d make on the next “Dancing with the Stars.” The *NSYNC star refused at first, but the babes begged: “PLEEEASE! And we’ll vote for you, honest!” Laughing, Joey got jiggy wid’ it, bustin’ tight moves and tricky twirls…until he suddenly slipped and bounced his butt off the newly waxed floor! “Okay, that’s enough of that,” he chuckled as the gals giggled. Rising, he rubbed his backside, then yelped: “OH, NO…I just bought these pants!” That’s right, folks – Joey had busted his moves… and his butt seam! With one hand covering the breached britches, Joey…er, split!