Justin Bieber calls out Floyd Mayweather Jr over Twitter

Canadian teen pop sensation and amateur Hilary Swank lookalike Justin Bieber has joined the ranks of boxing fans clamouring for a much-anticipated megafight between Manny Pacquiao & Floyd Mayweather Jr.Bieber tweeted his support in the early hours of Sunday morning after Manny Pacquiao's historic victory over Antonio Margarito in the Phillippines. The 16-year-old singer also called out Mayweather