What is "i don't think so"

phr. 1 I think what has been said is untrue. 2 (context sarcastic English) No (''used to refuse or decline something proposed'').

"I Don't Think So" is a song by American singer Kelis from her fourth studio album, Kelis Was Here (2006). It was written by Kelis, Max Martin, and Dr. Luke, and produced by the latter two. The song became popular with Australian audiences after being used in advertisements for the 2008 season of Big Brother Australia. Following the successful promotion of the show in Australia, the second season of American Gladiators used the same song and concept in their advertisements in the United States.

"I Don't Think So" debuted at number 49 on the Australian ARIA Singles Chart for the week of April 21, 2008, and ascended to number 29 the following week. It eventually peaked at number 27 in its third week on the run. The song is featured on the Australian compilation album Now: The Hits of Winter 2008.