A demonstrator participates in a rally sponsored by the Marijuana Party of British Columbia by smoking a giant hash-and-marijuana hash joint in downtown Vancouver April 20, 2005. Commonly known as 4/20, April 20 is a popular day among cannabis users. Reuters

To many, April 20 is just another workday. But to marijuana enthusiasts around the globe, 4/20 is a holy day, one to be considered above all others as a time to celebrate -- and consume -- cannabis.

The counterculture holiday doesn’t appear on any official calendar, but it’s pretty popular all the same. The origins of 4/20, aka National Weed Day, can be traced to Northern California where, in the 1970s, pot smokers began using the code “420” – the police code for Marijuana Smoking in Progress – as a reference to toking up.

Planning to observe 4/20? Here are 20 funny quotes to share on every pot smoker’s favorite holiday.

1. “That is not a drug. It’s a leaf.” -- Arnold Schwarzenegger

2. “They’ve outlawed the No. 1 vegetable on the planet.” -- Timothy Leary

3. “The drug is really quite a remarkably safe one for humans, although it is really quite a dangerous one for mice and they should not use it.” -- J.W.D. Henderson

4. “I think people need to be educated to the fact that marijuana is not a drug. Marijuana is a flower. God put it here.” -- Willie Nelson

5. “Forty million Americans smoked marijuana; the only ones who didn’t like it were Judge Ginsberg, Clarence Thomas and Bill Clinton.” -- Jay Leno

6. “When I was a kid, I inhaled frequently. That was the point.” -- Barack Obama

7. “I know you’re supposed to tell kids not to do drugs, but, kids, do it! Do weed! Don’t do the other stuff, but weed is good.” -- Kevin Smith

8. “To make marijuana against the law is like saying God made a big mistake.” -- Bill Hicks

9. “You bet I did, and I enjoyed it.” -- Michael Bloomberg

10. “I think pot should be legal. I don’t smoke it, but I like the smell of it.” -- Andy Warhol

11. “‎Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see.” -- Thomas Jefferson

12. “If you substitute marijuana for tobacco and alcohol, you’ll add eight to 24 years to your life.” -- Jack Herer

13. “It really puzzles me to see marijuana connected with narcotics ... dope and all that crap. It’s a thousand times better than whiskey -- it’s an assistant -- a friend.” -- Louis Armstrong

14. “I now have absolute proof that smoking even one marijuana cigarette is equal in brain damage to being on Bikini Island during an H-bomb blast.” -- Ronald Reagan

15. “Make the most of the Indian Hemp Seed and sow it everywhere.” -- George Washington

16. “If you grew up in the ’60s or ’70s and didn’t do drugs, I don’t trust you.” -- Danny Danko

17. “There are only two kinds of dealers. Those who need forklifts, and those who don’t.” -- Tom Forcade

18. “The other day they asked me about mandatory drug testing. I said I believed in drug testing a long time ago. All through the sixties, I tested everything.” -- Bill Lee

19. “Of course I know how to roll a joint.” -- Martha Stewart

20. “I have always loved marijuana. It has been a source of joy and comfort to me for many years. And I still think of it as a basic staple of life, along with beer and ice and grapefruits -- and millions of Americans agree with me.” -- Hunter S. Thompson