Kevin Federline AKA Britney Spears ex-husband wore a “America’s Most Hated” shirts for his WWE appearances in 2006-2007.
K-Fed’s intention was to promote his album Playing With Fire by starting a feud against John Cena…

Yes, on Raw January 1, 2007, the skinny ex-Britney Spears’s husband Kevin Federline DEFEATED John Cena 1-2-3 in a downright ridiculous no-disqualification match.

All of his WWE appearances did little to help K-Fed’s record sales; despite his prediction of selling half a million copies, Playing With Fire went on to sell 16,000 copies and his tour was cancelled. For comparison, pro wrestler and one-time rapper John Cena’s rap CD You Can’t See Me has sold 1.346 million to date… K-Fed probably did more money from his WWE appearances than from his album sales.
It seem that K-Fed was really the “America’s Most Hated”.

Source: http://www.wrestlecrap.com/inductions/kevin-federline-vs-john-cena/