It's 4/20 ... and you've NEVER seen Mike Tyson this happy!!
The boxing legend is now a full marijuana advocate and entrepreneur -- and to celebrate the biggest weed holiday of the year, he fired up a joint and explained to TMZ Sports why the day is so important to him.
Of course, 53-year-old Mike launched his "Tyson Ranch" weed biz a while back -- and now swears by THC ... saying he views it as "medicine" and raves that it's changed his life for the better.
Now, he views 4/20 as an important day -- because it symbolizes the beginning of the "revolution" to de-criminalize weed all over the world.
In between tokes, Tyson also revealed his dream celebrity smoking buddy -- explaining why he would have LOVED to spark up with Bob Marley.
"He is such an amazing man, I wish I had the opportunity to meet him."
Obviously, Bob passed away a long time ago -- but Mike says he's friendly with Marley's kids ... and even visited Bob's home in Jamaica!