Kid Cudi, whose real name is Scott Mescudi, was called as a witness by the prosecution. Mescudi, the "Pursuit of Happiness" rapper, was once in a brief relationship with Combs' ex, Casandra "Cassie" Ventura .

The 55-year-old hip-hop mogul has been charged by federal prosecutors with sex trafficking, racketeering conspiracy and transportation to engage in prostitution.

Kid Cudi took to the witness stand on Thursday to testify at Sean 'Diddy' Combs' sex-trafficking trial. Cassie alleged that Diddy reacted violently when she and Kid Cudi had a fling in 2011.