2009 MTV Music Awards

At the 2009 MTV Video Music Awards, Taylor Swift defeated Lady GaGa, Katy Perry, and Beyonce to take home the trophy for Best Female Video.
As a visibly humble, appreciative Swift took the stage and began her acceptance speech, Kanye West actually grabbed the microphone from her and declared that Beyonce - with "one of the greatest videos of all-time" - deserved to win.
The camera cut to Beyonce in the audience. She was horrified. Kanye (who drank Hennessy on the red carpet) ran away from the stage like a pathetic little bitch; and Taylor was left alone, embarrassed and speechless.
To the crowd's credit, they stood and applauded Swift, but the damage had been done. Later Kanye west apoligized to Taylor and she accepted.