SO MUCH TRASH TALK!!!
Jake Paul and Nate Robinson have signed the dotted line to fight in Sept. -- but they're already throwing verbal haymakers ... and the video is amazing!
23-year-old Jake is taking on the 36-year-old ex-NBA player on the undercard of the big Mike Tyson vs. Roy Jones Jr. fight after a war that started on TMZ Sports.
Long story short ... Nate called out Jake after watching the YouTube star beat up a couple of social media influencers in his first boxing matches.