The Correct Answer was "O-V-Y"

U.S. Customs and Border Protection official: "Citizenships?"

Me: "Canadian."

Border guard: "Where you boys headed?"

Me: "UDM law school."

Border guard: "What time does class start?"

Me: [looks at dashboard clock: 8:30] "Right now."

Border guard: "Why you late?"

Me: [gestures vaguely to passenger seat] "His fault."

Paul: "It's true."

Border guard: "Your vehicle?"

Me: "Yes."

Border guard: [looks at mirror behind truck, reading license plate] "N6A ..."

Me: "1 ... 4 ... 7?"

Border guard: ...

Me: "Was I close?"

Border guard: "Nah." [waves car through anyway]

Paul: [laughter]

Some days, America is awesome.