SE02EP31: Knight and Day (2010)

"Hey what should we call this film?"
"How about we name it after Tom Cruise's character?"
"So 'Miller'?"
"No his character's actual name."
"What, Knight?"
"Yeah!"
"But you don't learn that until the end of the film."
"Doesn't matter...oh and we should add 'and day' afterwards.
"Who is Day in the film?"
"Nobody."
"So why Knight and Day?"
"Because that's the expression!"
"Uh huh."