"Last Friday Night (T.G.I.F.)" is a song by American recording artist Katy Perry. The track was written by Perry, Dr. Luke, Max Martin, and Bonnie McKee and was produced by Dr. Luke and Max Martin. It is the fifth single from Perry's third studio album, Teenage Dream, and peaked at #4 on the US Billboard Hot 100 in just its fourth week on the chart and #6 on the Canadian Hot 100. Like all of Perry's previous Teenage Dream singles, it topped the Hot Digital Songs chart. As of June 29, 2011 "Last Friday Night" has sold 571,000 copies.The accompanying music video for the single marks the debut of Perry's alter ego, Kathy Beth Terry.
