I have to go with The Invention of Lying. It is one of two movies (the other being Year One), that I simply couldn’t finish watching. Ricky Gervais is dreadful. Jennifer Garner couldn’t act her way out of a sack, and Robb Lowe turns in his most criminal performance since the kiddie porn tape.
Even the addition of Nate Corddry, Tina Fey, Jonah Hill, Louis C.K., and Jeffrey Tambor to the cast were unable to make this watchable. It is an affront to movies.