The comedy, which features Stiller, Jack Black, Robert Downey Jr. and Tom Cruise, grossed $26 million in its first weekend on release in America, giving the film a $37 million five-day tally.
But there's still plenty for the cast and crew of Batman's The Dark Knight to celebrate - by scoring a healthy $16.8 million over the weekend, the film becomes the second-highest-grossing film ever, according to new estimates.
The action movie, starring Christian Bale and the late Heath Ledger, has now amassed more than $471 million in U.S. ticket sales. Only Titanic has made more at the box office.