There are so many uses of this word found in this movie, someone brilliantly found the time to edit the film down to only the "fucks" into 4 1/2 minutes.
Classic scene using the word, "Fuck"
Nicky Santoro: Listen to me Anthony. I got your head in a fuckin' vise. I'll squash your head like a fuckin' grapefruit if you don't give me a name. Don't make me have to do this, please. Don't make me be a bad guy, come on.
Tony Dogs: Fuck you.
Nicky Santoro: This motherfucker, you believe this? Two fucking days and nights! Fuck me? *Fuck me?* You motherfucker!
[turning the crank]
Nicky Santoro: Fuck my mother? That's what you fucking tell me? You motherfucker you!
After Wesley lets out his anger at the office he greets his 'friend' with a friendly smash to the head from his keyboard, knocking the keys loose and flying to screen with a lucid "FUCK YOU" brilliant. (The second "u" is a tooth) (Thank you Kris for the suggestion)
The scene where Eric Bana is showing the guys his favorite sports and trying to explain it to them.
There aren't any clips of it on youtube yet; but if anyone finds it please let me know, it's hilarious!