The entirety of the conversation between Osbourne Cox and Chad Feldheimer (and later Linda Litzke) over the phone.
Chad Feldheimer: I thought you might be worried...
Osbourne Cox: Worried?
Chad: About the security...of your shit.
Chad (late in the conversation, after he has already confirmed several times): Osbourne Cox?
Chad (after hanging up on a very angry Osbourne Cox): I am very fucking surprised he did not give us that reward.
"WHAT THE FUCK ARE YOU DOING IN HERE, YOU FUCKER?!"
"I'm not here representing Hardbodies."
'I know you. You're in LEAGUE with that moronic woman. You're part of a LEAGUE of morons.'
"You think it's a Schwinn!"
Chad's "Hi, please don't kill me" smile before Harry shoots him.
That scene one of the very few truly sympathetic characters in the plot is having his head hacked to pieces, it's all very upsetting... and then the scene cuts to the security guy trying to explain the incident to his boss. I saw the movie in the cinema and it was the most impressive control of audience emotions I've ever seen. The whole audience went from distraught to cracking up simultaneously.
Any scene where Chad tries to blackmail Osbourne Cox.
In addition to the gag, it's set up amazingly well as the movie sets up what Harry is building as something important.