Shadecorp- a serious answer for the munchkin- Show her a calendar that has a Feb 29th. That Leap Year day was added to keep the calendar in pace with the actual movement of the earth, and the seasons (one trip around the sun is 365.25 days).
The Leap Year was introduced in OUR calendar in about 1582. The Mayans did not use leap years. So since 1582, every 4 years, we had an extra day, meaning that the Maya calendar moved AHEAD one day.
THEIR calendar actually reached 21 Decemeber 107 days ago. The end of the Maya calendar has already happened, and we are still here. (Well, I am- don't know about you....)
Tell her to worry about pimples, politicians, and whether that boy with the freckles really likes her- but not about the calendar.