Total Recall. The original.
"Howdy, stranger! This is Hauser. If things have gone wrong, I'm talking to myself and you have a wet towel around your head. Now, whatever your name is, get ready for a big surprise. You are not you, you are me."
To be fair though, the remake is still pretty good. The main reason the original still beats it is purely because of Arnold, who simply by himself adds a layer of corniness and comedy just by it being him.
From the novel We Can Remember It For You Wholesale by Philip K. Dick.
(By the way, Philip K. Dick and Harlan Ellison are awesome writers. - I love "Angry Candy", "Mefisto in Onyx" and "The Three Stigmata of Palmer Eldritch")