BOSTON -- Once a cool, cheap slip-on for the beach, the flip-flop is now the hottest trend in footwear.

NewsCenter 5's Liz Brunner reported Wednesday that President George W. Bush was photographed with the Champion Lacrosse team from Northwestern University, many of whom were wearing flip-flops.

If your idea of a flip-flop is the rubbery Woolworth's type, footwear has changed.

Flip flips, or thongs, as they once were called, are all grown up, in all shapes and sizes. And fashion trend setters insist they fit just fine with formal or informal wear, at work or the beach.

"The young and the hip of all ages are buying flip flops. You want to dress it up, or dress it down, that's why they are so popular -- the versatility of them," Lord and Taylor spokeswoman Colleen Harkins said.

"I have about 12 pair, from casual to dressy. I wear the dressier ones to work," one woman said.

Judging from a sidewalk survey, so do many others.

"I wear them to work all the time, going to work as we speak," one man said.

"I wear them to the prom, to homecoming, and they're comfy under dresses," another person said.

From Gucci to Burberry, designers are spewing flip-flops out faster than office managers can say dress code. But etiquette expert Jodi Smith says toe the line.

"In a more conservative office, thongs are not a good choice. But if you are in a very casual, hip, young environment, if your boss wears flip-flops, watch what kind they wear. You want to know where you are going and you want to match either your host or your boss," Smith said.

"No matter what your politics are, if you are invited to the White House you owe respect. We show respect through our attire, behavior and communication. The attire was fine from knees up, and it fell down on footwear," Smith said.