In case you missed the big news, Brock Lesnar has potentially violated USADA's anti-doping policy, which not only puts him in position to be banned from UFC competition for 2 years, but also jeopardizes his UFC 200 win over Mark Hunt. The out-of-competition drug test was taken just about 2 weeks out from UFC 200, and USADA rules state that "an Anti-Doping Policy Violation occurring during, or in connection with, a Bout may, upon the decision of UFC, lead to Disqualification of all of the Athlete's results obtained in that Bout." In other words, Lesnar's win can be a DQ loss, and the win would instead go to Hunt.
Roy Nelson feigned his surprise upon hearing the big story, tagging Hunt's username in his tweet. Hunt responded to Nelson's tweet, noting how many times he's fought someone who would later be found to have failed a drug test.
Hunt is just a few months removed from his KO win over Frank Mir, who promptly failed his drug test and is otherwise asking out of his UFC contract. In 2013, Hunt fought to a draw with Antonio Silva, who later tested positive for elevated testosterone levels, which resulted in Silva getting a no-contest on his record, while Hunt kept the draw.
While we're on the subject, the following Mark Hunt opponents have also failed drug tests at some point in their respective careers: Brock Lesnar, Frank Mir, Antonio Silva, Wanderlei Silva, Josh Barnett, Alistair Overeem, Ben Rothwell, and while he technically didn't fail, Mirko Cro Cop's admission of using HGH may as well count.