Mayan Calendar, this is why it stops on the 21st

The guy chiseling the calendar was named Carl, and his wife was named margaret.
Carl was a loner,you know the type. No hobbies stayed inside and never participated in ritual killings. Every time they torn someones heart out he was off chiseling on his calendar. finally Margaret came into his grass hut man cave and said "really Carl, 2012?". When does it stop? What the hell, thats 5,000 years away. She said "I am taking the kids and going to my mothers", she then said "either quit chiseling on the calendar or I'm leaving you".
At first Carl thought, friggin bitch go ahead and leave, but after a few moments common sense took over. He said, your right, 5,000 years away who the hell is going to care anyway. He put his hammer and chisel down and started a new hobby. Carl finished out his years playing the game he invented which consisted of kicking severed human heads into an opposing teams goal. That game is called "Soccer" today, now you know the rest of the story.

That is why the calendar stops December 21, 2012.