A Detroit Lions fan berated Marshall on social media recently for comments he made during an interview last year, when Marshall called the Lions his team's "little brother."
Marshall was quick to respond. The man only gets the money if he beats Marshall in the fight. Should he lose, the Lions fan has to volunteer 100 hours at an orphanage.
"I give you $5K to get in the ring with me," Marshall tweeted.
The Lions fan responded by asking for $25K and for the fight to be in his city.
"25 it is. Ha! You thought I wouldn't say yes." He added in another tweet: "And you have to apologize to my mom."