A particularly reticent Kristen Stewart joined Jimmy Fallon for a hilarious game of Word Blurt on Tuesday, Aug. 11's Tonight Show — and the Twilight alum wasn't being fooled by any of Fallon's platitudes!

Fallon tried to encourage the 25-year-old actress to play by telling her that if her blurted responses were the same as his, it would prove they were destined to be best friends.

"You have so many besties, I don't want to hear that anymore," Stewart replied, before admitting the game was making her seriously nervous.

"I’m not very good at the whole improv joke thing, so to even just say a word is going to be hard," she protested. "Okay, let's just go!"

Turns out Stewart was right! While the first couple of words (“tequila” and “selfie”) did manage to elicit responses from the American Ultra actress, they didn't match Fallon's. And when faced with the words “marshmallow” and “Lenny Kravitz,” she struggled to say anything at all!

"Penis!" yelled out Fallon, when he read Kravitz's name (as Us Weekly reported previously, the rocker experienced a very embarrassing wardrobe malfunction during a concert in Stockholm earlier this month), but Stewart was reduced to silence.

"Now I'm totally influenced by that," Stewart protested. "And I'm going in that direction and I feel weird, so maybe, um....piercing?"

In the end, despite Stewart's nerves, it turned out there was one thing the duo could agree on. Watch the whole video above and see what the pair came up with when faced with the word “mistake!”

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