The 42-year-old, who was tasked to sing the 'Star-Spangled Banner', reworked the tune to more of a jazzy beat.
However, she was slammed by the Twitterati, with a few calling it the 'worst rendition ever'.
"Literally dying at these reactions. Fergie with the worst rendition ever," wrote one user.
"FROM NOW ON: When you fail at something while demonstrating an insane level of confidence, you must say "I Fergged up" #fergie #NationalAnthem," wrote another Twitter user.