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The actor admits he hates when people say "You know nothing, Jon Snow," and shares how his brother worked it into his Best Man speech.

Kit Harington dropped by "The Tonight Show" and proved that he may just be the perfect cast-member of HBO's epic "Game of Thrones" to lob spoiler questions at. Especially if he can answer with just winks and blinks.

The man who's portrayed Jon Snow on the hit series since the beginning admitted that there is one phrase that has haunted him since it was first uttered on the show. Ironically, he wound up marrying the actress who first uttered the words, "You know nothing, Jon Snow."

That means that when they're out they always have it shouted at them. "I hate it when people say it," Harington admitted to Jimmy Fallon on "The Tonight Show" Thursdayd night.

That's probably why his own brother found a way to work it into his Best Man speech, because brothers are reliable like that. But even Harington had to imagine it was "quite sweet, actually."

"He said, 'But looking at the woman you're marrying, it shows you do know something, Jon Snow,'" Harington shared. The actor married his "Thrones" co-star Rose Leslie on June 23, 2018.

Before getting into plot-related spoilers, Fallon had to ask about a rumor he'd heard that Harington actually showed up at a costume party dressed in a Jon Snow costume, which the actor had to admit was true. On top of that, it was for his wife's 30th birthday party.

But it wasn't a "Thrones"-themed party, it was rather a "bad taste" party. "So I thought about it and I thought, you know, what's worst taste than going as the character you play in the show you're on," Harington said. "It's really bad taste. So I did, thinking this was really funny. "

The problem was that not everyone they'd hired to work the party knew the theme of it. "So they just saw me dressed as my character from 'Game of Thrones," he said. "It's like, 'You sad, sad man.'"

When it finally came time to get to the spoiler-y portion of the interview, Fallon decided that rather than have Harington say anything that might get him into trouble, he could just wink for yes and blink for no.

There was just one problem.

It turns out Harington can't quite wink, and it instead comes out looking like a cross between a wink and a blink. This means that all of his answers looked exactly the same. So he might have told us if Jon Snow dies, rides a dragon or worse, but we'll never know for sure.

The truth will finally out when the final season of "Game of Thrones" kicks off on Sunday, April 14 at 9 p.m. ET on HBO.

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