The real 'secret' meaning behind cannabis event 420 - and why some even think it is about Adolf Hitler

It's one of the most important holidays of the year for cannabis smokers but what is the 'secret' meaning why people celebrate it on April 20 every year and what bizarre connection does the holiday have the Adolf Hitler? 

April 20, or 420 as it is known, is a day where millions of weed smokers come together to mark an unofficial holiday dedicated to marijuana. 

Potheads in 38 US states can enjoy the day legally while in the other states and here in the UK drug users will partake in the holiday illegally. 

London's Hyde Park has become a popular destination for 420 as thousands of smokers descend on the royal park to light up a doobie often in full view of police.

The origin of the popular tradition is somewhat shrouded in mystery with many modern-day myths popping up about where it came from. 

There are many stories behind the significance of the number in stoner culture, but the most common is that 4.20pm is touted as the best time of the day to start smoking the narcotic

London's Hyde Park has become a popular destination for 420 as thousands of smokers descend to light up a doobie often in full view of police. 

Cannabis users gather in large numbers in Hyde Park to take part in the 420 day rally

According to TIME Magazine, one of the most concrete theories about the roots of what became 420 was started by a group of students in California in the 60s. 

The students, Steve Capper, Dave Reddix, Jeffrey Noel, Larry Schwartz, and Mark Gravich, would get together by the school's statue of chemist Louis Pasteur to smoke. 

They would meet at the rendezvous point at 4.20pm. But the time had no significant meaning, it was just the time when their extracurricular activities ended.

As Marijuana was still illegal in California in the 60s the group, who became known as the 'Waldos' soon started using 420 as a secret code for going for a smoke.

4.20pm is now often touted as the best time of the day to start smoking the narcotic. 

Other theories about the origin of the holiday are also connected to California. Some people believe 420 was a police code in the US state for marijuana. 

A cannabis smoker at the gathering in Hyde Park, London this afternoon

Perhaps the most bonkers theory involves Adolf Hitler whose birthday coincides with the holiday, but this is almost certainly a coincidence

According to the Daily Star, others think it is the number of active chemicals in the drug. 

Another theory revolves around Bob Dylan's song Rainy Day Woman #12 & 35 as the number 12 multiplied by 35 equals 420. 

Mr Dylan did famously enjoy smoking weed in the 1960s and it is widely believed he was the first person to get fellow rock and roll legends the Beatles high when they met in New York in 1964. 

Perhaps the most bonkers theory involves Adolf Hitler whose birthday coincides with the holiday, but this is almost certainly a coincidence. 

Wherever, 420 came from with over a million smokers marking the occasion, both legally and illegally, the counterculture holiday looks here to stay.