Former Lions receiver Calvin Johnson spent nine seasons in the NFL, and although he was never suspended during his career, he definitely could have been, and that's because he used to break one certain NFL rule after every game. 

During a recent interview with Sports Illustrated, Megatron revealed that he smoked marijuana after nearly every game he played in from 2007 until his retirement in 2015. According to Johnson, he used the drug to help ease the physical pain that he would feel after each game, and he also used it because he was alarmed by the rampant opioid abuse that he saw going on in the NFL

"When I got to the league, [there] was opioid abuse," Johnson said. "You really could go in the training room and get what you wanted. I can get Vicodin, I can get Oxy[contin]. It was too available. I used Percocet and stuff like that. And I did not like the way that made me feel. I had my preferred choice of medicine. Cannabis."

The reason Johnson was smoking for medicinal purposes so often during his NFL career is because he was almost always in serious pain after each game he played in. Not only did he suffer multiple ankle injuries during his career that eventually led to his retirement, but Johnson also says that he suffered multiple concussions during his time in Detroit. 

According to Megatron, he suffered at least nine head injuries in a career where he was never listed on the Lions' injury report with a concussion. As a matter of fact, the one time he did go public with having a concussion came in 2012 and that ended up causing a minor controversy. After Johnson came out and said he had suffered a concussion, the Lions said he was mistaken and that it wasn't a concussion, and Johnson later agreed with them. 

Megatron now says that he only changed his story in 2012 because the Lions made him. 

"I knew I was concussed because I blacked out. I wasn't seeing straight," Johnson told Sports Illustrated. "And they wanted me to change my story."

Although he suffered multiple concussions, Johnson explained that he would just play through them, because that's what he was used to doing. 

"Bam, hit the ground real hard. I'm seeing stars; I can't see straight," Johnson said. "But I know in a couple minutes I'm gonna be fine. Because I've done that plenty of times before."

In the end, Johnson's constant injuries ended up being a big reason why he retired following the 2015 season at the age of 30. After using marijuana for nearly all of his career, Johnson is a big proponent of using the drug for medicinal purposes. As a matter of fact, Johnson is so on board with using pot as a way to cope with pain that he's looking to open his own medical marijuana business in Detroit

Despite only playing nine seasons, Johnson currently ranks 30th on the NFL's all-time list for most receiving yards (11,619) and 22nd on the list of most all-time receiving touchdowns (83).