It is powerful. It is secret. It is unreturnable, even with a receipt, at most department stores.

The thong.

It had seemed, until this past weekend, that the thong achieved its pop culture pinnacle a long decade ago. That’s when a certain intern flashed hers at a certain president who, to the disbelief of everyone except perhaps that president’s wife, reacted almost exactly like a dog stumbling upon a stockpile of Slim Jims. Unwrapped Slim Jims.

Naturally, that president denied this behavior for quite some time, presumably out of intense embarrassment. But maybe he shouldn’t have. Since most men understand the pull of that pert undergarment, publicist Marty Appel said, “He could have avoided a lot of trouble if he just said, ‘Hey — she showed me her thong.'”

For the greater part of his career, Mr. Appel worked as press agent for the New York Yankees, which means that for the past few days he has been following with interest the latest thong in the news: Jason Giambi’s. In an interview with Portfolio magazine, Mr. Giambi admitted that when the going gets tough, the tough wear women’s underwear. Or at least, he does. Apparently he favors a gold lame, tiger-print model. Those Yankees love their stripes.

While you’d think an admission like that might make a guy a little less inclined to show his face — or any other body part — in public any time soon, the fact is, Mr. Giambi was man enough to do so. And, like any undergarment worth its elastic, the thong did not let him down. Though he’d been batting a dismal .191 so far this season, on Saturday, a day after his startling admission, the troubled slugger stepped up to the plate and belted one out of the park: The right man at the thong time. (If, indeed, he was wearing it. Since a thong exists to eliminate visible panty lines, there’s really no way to tell.)

Anyway, the Yankees still lost. Then they lost again the next day, making one wonder about the mercurial nature of luck — and Lycra. Mr. Giambi, however, swears by both. He even told Portfolio that in the dozen years he’s owned the tail-tickling talisman, he has lent it out to other players when they hit slumps. Among them were Derek Jeter, Bernie Williams, Johnny Damon, Robinson Cano, and Robin Ventura — making you picture the team in a whole new way.

“When I heard about the baseball players and the thong, I thought, ‘Well, this is a video I have,'” said my friend Christopher, who’s gay. “Even as an out man who’s very liberal on social issues, I find myself on some level appalled.”

“You’d think that guys who make $500 million a year for the Yankees could have afforded their own thongs,” another guy opined.

Which brings us to the idea of icons. Icons in thongs.

Aren’t ballplayers supposed to be role models (when they’re not shooting steroids)? Do we really want more boys in g-strings? Or even girls? Mothers today have enough trouble luring their daughters away from Lolita-wear. “My 12-year-old knows about them and she wants them — absolutely,” a mother of two told me. “I said, ‘No way! Forget it! Wait until you’re, like, 25 and buy them yourself.”

Her fear has a simple source: Sex. While loincloths have been around since at least King Tut — who was buried with more than 100 handsome pairs — the female thong first took America by storm in a sex-soaked scandal right here in New York City. Dancers donned the things when Mayor LaGuardia ordered them to wear something — anything — more modest during the 1939 World’s Fair.

It took another generation or so, but sometime around 1980, the item leapt from stripper gear to hipster standard when it made its way up from Brazil, along with all the other grooming standards that country bequeathed us. The 2000 “Thong Song” by Sisqo just cemented the silly string’s salacious status. It has been engaged in a good undies/bad undies war with old-fashioned underpants ever since.

Now that it has become a ballpark basic, however, perhaps the thong is about to undergo one last transformation: From tarty triangle to jock basic. Gatorade for the groin. Whatever. Nike could launch a line of them. Come to think of it, so could the Yankees.They need to finance that new stadium, right? I can hear it now: Get yer peanuts! Popcorn! Panties!

After all, this year they’ve been really good at bringing up the rear.

lskenazy@yahoo.com