Jake Paul wasn't kidding when he said he'd sue the hell outta anyone who claimed his fights are staged -- he's teamed up with powerhouse attorney Alex Spiro to pursue legal action against the people spewing lies about his boxing career.
TMZ Sports has learned ... the YouTuber-turned-boxer retained one of the biggest lawyers in the biz to be in his corner -- as the allegations his bouts are scripted have done some serious damage to 28-year-old Paul, his partners and the entire sport's reputation as a whole.