I was born on a leap-year, on that elusive date of February 29, some years back. Thus technically giving me only one day every four years to celebrate my birthday.
I can count my age like regular people do, adding one to my age every year. Or I can also count it in terms of leap years, thus adding one to my age every four years, just for fun. So once my friends hit eighty, I can still claim to be twenty years old and be truthful about it somehow.
One disadvantage of being a leap-year baby though is not having my birth date on yearly calendars like most people do (unless I add an imaginary box right next to February 28). Nor can I claim a single day each year to be my birthday. Thankfully, we leap-year babies don't necessarily need to follow the order of things, unlike people born on other dates.