You know it. It’s that line, when the hero / villain / sidekick pulls out The Big Guns.
Two off the top of my head:
“Dodge this.” --Trinity, The Matrix
“Assimiliate this!” --Worf, a Star Trek movie that I can’t remember the full title of.
And, of course:
“Say hello to my little friend!”
Well? 
Is a movie title permitted? I’m thinking Analyze This.
My favorite such exchange is in Dracula 2000.
A vampire has our erstwhile hero pinned to the ground, whereupon our hero shoves an antique cross that belonged to his employer Van Helsing in the vamp’s face.
Vamp : “Sorry, sport, I’m an athiest.”
(The hero trips a hidden catch on the cross, revealing a long silver dagger that flicks out of the base of the cross)
Hero : “God loves you anyway.”
Crocodile Dundee: “That’s not a knife. Now that’s a knife!”
Malone, The Untouchables: “Isn’t that just like a wop. Brings a knife to a gun fight!”
Because somebody’s gotta say it:
“This . . . is my BOOM STICK!!” (Army of Darkness)
“Hey Terrorists! Terrorize this!” -Team America