UFC great Jon Jones is widely regarded as one of the best MMA fighters in history, but his career has been marked by several controversies. One major incident was the failed drug test that led to the cancellation of his rematch against Daniel Cormier in 2016, resulting in aone-year suspension from USADA.During his appearance on The Joe Rogan Experience podcast in December 2016, Jones explained the reason for his failed drug test, stating:"So I took an off-brand Cialis [a drug used to treat erectile dysfunction] pill. It wasn't an actual Cialis. But it was described to me as being a Cialis. So I thought it was a Cialis and I just took it."When asked why he felt the need to use Cialis, Jones gave a hilarious explanation, stating:"I have a huge [genitalia] Joe. It's too big."Jones added that he had used sexual enhancement pills before this incident. However, the one that led to him testing positive for performance-enhancing drugs was sourced from a friend's pharmacist girlfriend, and derailed his career in a significant way.Check out Jon Jones' comments below (0:30):Jon Jones sheds light on the events leading to the failed drug test, and his response to the situationJon Jones was expected to rematch Daniel Cormier in a title unification bout at UFC 200 on July 10, 2016. According to him, he used the Cialis pills containing banned substances from June 14 to 16 and was completely unaware of the consequences.In the aforementioned appearance on The Joe Rogan Experience podcast, Jones explained that he was hospitable towards the USADA officials who came to collect his samples a few days later. However, the test returned positive, marking one of the most controversial chapters of Jones' professional MMA career. He learned of his test result through his manager Malki Kawa, who informed him:"Right before UFC 200, my manager Malki Kawa calls me over to his hotel room. He's like, 'Hey I want to talk to you, man.' I was like, 'What's going on?' He goes, 'You're not going to be fighting.' I said, 'What are you talking about?' He's like, 'You didn't pass your drug test.' The level of hurt and confusion... I literally had an anxiety attack. And, I never had one of those before." [3:25]He added:"I felt like the whole room came down on me. And I couldn't breathe. I remember opening this hotel room window, looking for a balcony so I could just breathe. I calmed myself down, and I instantly started thinking about the weight of the world on my back. I knew that I wasn't going to be fighting, a few hours before everyone else. And I could already start hearing everything."In their verdict, USADA ruled that Jones was careless rather than a cheat. Meanwhile, Jones' opponent, Daniel Cormier, was also distraught after the fight cancellation and ended up fighting Anderson Silva in a short-notice fight.Check out Daniel Cormier's reaction to the cancellation of the fight