Having a leap-year birthday was more of a quirk than a nuisance for Teresa Wedeen, until she was looking to buy her first legal drink in 1989.

The Aurora resident, born Feb. 29 -- which falls once every four years -- recalls being out with friends near the Fox Valley Mall, and heading to a local bar Feb. 28, which is the day she celebrates her birthday in non-leap years.

"They made me stand outside of the bar until midnight, when technically it was March 1, and then they let me in legally," said Wedeen, who turns 48, or technically 12, today. "But at the time, you don't think about that. I remember insisting, 'I'm 21.'"

Over the years, other little difficulties have cropped up -- Facebook, for instance, doesn't recognize Feb. 29 as a birthday for account holders like Wedeen. And membership programs that promote giveaways and discounts on one's birthday arrive only once every four years.

Deanne Slabenak-Henle of Plano recalls doctors warning her 16 years ago that she'd likely deliver her twins far before their March 31 due date.

"I said, 'As long as we can avoid Feb. 29, because I really feel like that's a generic birthday,'" she said.

But Frankie and Lexi Szot chose to enter the world that day anyway.

Leap years exist in order to keep the calendar years synchronized with the season. While a calendar year has 365 days, the earth's revolution around the sun takes slightly longer, about 365 days and six hours. With an extra 24 hours -- a full day -- accumulating every four years, an extra day is added to the calendar.

The Honor Society of Leap Year Day Babies boasts roughly 10,000 members, with an estimated 4 million "leapers" living around the world. Leapers include former Pope Paul III, actor Dennis Farina and rapper Ja Rule, according to the society's website.

Each leap year, Slabenak-Henle said, her family holds a "big blowout" for the twins, celebrating their leap year birthdays like milestones. While the menu and guest list have changed over the years, there's always been one constant -- a frog theme to allude to the 29th.

Frankie and Lexi, who are paternal twins of opposite sexes, say they embrace their rare birth date because it's one more thing that makes them unique. They're the only leap year babies they know.

"Our friends, they make fun of it in a joking manner, some don't really understand it," Lexi Szot said. She describes leap year celebrations "as more exciting because my parents like to make it as special as possible."

Wedeen said she didn't know anybody else who shared a leap year birthday until later in life. "As I got older, I'd go out to dinner for my birthday and somebody would come and sing happy birthday," she said. "Occasionally someone else would come up to me, and say that's my birthday too."