It's Dec. 21 and Twitter folks are tweeting as usual, making jokes and sharing news links about the day's top headline: the world still exists. But wait, it is still Dec. 20 in other parts of the world, isn't it?

People who have marked Dec. 21 on their calendars have different to-dos for the day. Others are out to party, some others log on to web sites which streams space monitoring videos. And then there were others who had planned to climb a French mountain to wait for a UFO.

(Read: Mayan Calendar End of the World Plea from French Mayor: 'Do not come to Bugarach')

On Twitter, people are sharing jokes and memes generally to celebrate being alive. In fact, some researchers have said the Mayans would be celebrating Dec. 21 as the modern world celebrates New Year's Day. As much as scientists try to explain things only got lost in the translation, doomsday preppers are not leaving anything to chance. Some of them have even bought underground doomsday shelters in case the Mayan calendar end of the world prediction proves to be accurate.

Some doomsday efforts are too strange for others, but at the end of the day, what matters is that there is still something to do. The world still exists. The living can still choose to live the way they want. And some of those who want to have fun take to Twitter for a few laughs.

12/21/12 Meaning and Mayan Calendar End of the World Beliefs

Here are some 'End of the World' tweets from users around the world. Start the accompanying slideshow for some images.

Everyone's making end of the world jokes like there's no tomorrow - ‏@GivUrHeadAShake

I'm not saying I believe the world will end tomorrow, but there is a lot of chocolate in my house that shouldn't go to waste. - @QuiltingMuriel

Wow, everyone is busting out these 'end of the world' jokes like there is no tomorrow. - Mary Delaney ‏@mairs

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