They Live (1988)
This film has the protagonist – who has just found out that the broken Reaganite capitalist nightmare is the result of widespread well-concealed alien control – carry a shotgun into a small convenience store (IIRC) and exclaim, "I am here to kick ass and chew bubblegum... and I'm all out of bubblegum."
Thirty years later, I still can't help but think of the missed opportunity for the cashier to respond dispassionately, "Candy and gum, second aisle."