No one really knows why for sure, but across the country April 20th has become the unofficial marijuana smoking day. The mystery surrounding today's festivities haven't stopped people from celebrating, including celebrities. Many famous actors, musicians and organizations posted messages on Twitter this Friday, April 20 to tell their fans and followers to have a happy 420. Here are some of our favorite tweets.

Rihanna: 420 starts with Marley #youngwildfree

Snoop Dogg: smoke one wit me n @willienelson #rollmeup #snoop420.

Talib Kweli: Happy 420.

Cypress Hill: Happy 420! Blaze em if you got em.Tonight in Denver at the Ogden cypress hill 420 show. This will stream live on

Wiz Khalifa: Special Daaaaaaaaay!

Wiz Khalifa: Im Gonna Be Tweetin Pictures Of Weed All Day. Don't Mind Me :-)

Wiz Khalifa: Shut Up And Smoke

Rob Thomas: happy 420, to those who are inclined to care about such a thing. :)

Slightly Stoopid: Happy #420 Stoopidheads. Travel day for us, but first, time to light one up.

Cheech Marin: Happy 420 to all and everybody. Legalize it

Snooki: Happy 420 was cool when I was 16. -_-

Craig Robinson: Happy 420!!!

Michael B Jordan (actor): Happy 420 Herbivores!!

Huffington Post: Happy 420! We tried to think of 420 facts about marijuana and the economy, but only got to 16

Anonymous: Good morning, followers! Happy #420 and get ready for #OpCannabis! Time to go #wakeandbake (for some of us)

Darth Vader: Happy 420, Yoda just got so high, his huge eyes are practically shut.

Darth Vader: Happy 420, I just lit up a joint with my lightsaber.