There's no doubt that John Cena has suffered some humiliating losses throughout his 23-year career, such as being defeated by John Laurinaitis, but there's truly nothing more embarrassing than his singles loss to Britney Spears' then husband and American rapper Kevin Federline.
During WWE's "Celebrity Guest Host" era, Federline appeared alongside Johnny Nitro and Melina on "WWE Raw" where he promised to play music from his one of his albums, but he changed his mind after being ruthlessly booed by the fans in attendance. Cena, who was the current WWE Champion at the time, then interrupted Federline, delivered an insulting rap, and hit him with an Attitude Adjustment. However, what seemed like a one-off appearance turned into a short rivalry, as "K-Fed" slapped Cena across the face the next week and would also make his presence known at Cyber Sunday to prevent the future WWE Hall Of Famer from defeating Booker T for the World Heavyweight Championship. The following night on the New Year's Day edition of "Raw," Federline would challenge Cena to a No Disqualification match.
During the contest, Federline quickly took advantage when Nitro immediately interfered in the match, allowing the musician to deliver a low-blow to Cena. Just moments later, Federline received additional assistance from Umaga, who would challenge Cena for the title later that month at the WWE Royal Rumble. Umaga unleashed a brutal attack on Cena, which allowed Federline to easily pickup the three count, resulting in one of the most embarrassing losses of the 17-time World Champion's career. Later that night, Cena would get his revenge by delivering anAttitude Adjustment to Federline, but unfortunately the match will never be erased from the record books.
