Well it's official...
Interactive encyclopedia Wikipedia has determined that British writer/director Gary Oldman's 1997 award-winning Nil by Mouth used the F-word more times than any film in history -- 470 times in 128 minutes, or an average of 3.67 times per minute. Runner-up on the list was Martin Scorsese's 1995 gangster flick Casino with 422 F-words over 178 minutes, or 2.37 per minute. Close behind was 2002's Martin Lawrence Live: Runteldat which used 347 F-words in just 113 minutes, or 3.07 times per minute.
This coming from the news page on IMDB.com.
I guess you all knew this anyways, hehe.