"Then, after showing Homer the moccasins he’s wearing and saying that there’s a pair waiting for him in the closet, he takes off the shoes, throws them out the door, and asks Homer if he’s ever seen a guy say goodbye to a shoe. “Yes, once,” Homer replies. In a testament to the obsessive nature of Simpsons fandom (and to Sayre’s law), the throwaway exchange has sparked one of the most heated and least important debates in history.
"Some believe that Homer is talking about what he’d just seen. Others are sure that Homer is referring to a different guy he once saw saying goodbye to a shoe. A recent BuzzFeed poll conducted about the meaning of the line collected 109,000 votes. The interest generated by the dispute is further proof that if necessary for survival, the internet could subsist solely on Simpsons minutiae. (In fact, Jonah Peretti practically built BuzzFeed on this sort of ephemera, a Scorpioesque feat in itself.)
So was Homer thinking about the present or the past?
“I probably thought it was a previous time,” Castellaneta, who improvised the line, told BuzzFeed, “but it is funnier if it means he saw it at that moment.” Weinstein concurred: “He’s referring to something in the past. It would take too many mental moves and twists for the joke to be that he’s referring to what Hank Scorpio just did.”
The whole article about You Only Move Twice is worth a read: