Jessica Biel and Jimmy Fallon try to guess Justin Timberlake's responses to a series of random questions in a competition to see who really knows him best.

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The Tonight Show Starring Jimmy Fallon features hilarious highlights from the show including: comedy sketches, music parodies, celebrity interviews, ridiculous games, and, of course, Jimmy's Thank You Notes and hashtags! You'll also find behind the scenes videos and other great web exclusives.

Best Friends Challenge with Justin Timberlake and Jessica Biel
http://www.youtube.com/fallontonight

#BestFriendsChallenge
#JustinTimberlake
#JessicaBiel

Jinx Challenge with Chris Hemsworth
Jinx Challenge with Chris Hemsworth
Try Not to Laugh Challenge with Benedict Cumberbatch
Try Not to Laugh Challenge with Benedict Cumberbatch
Kevin Hart FaceTimes Dwayne Johnson While Co-Hosting The Tonight Show
Kevin Hart FaceTimes Dwayne Johnson While Co-Hosting The Tonight Show
Ellen Looks for the Mystery Celebrity Hiding in Her Audience
Ellen Looks for the Mystery Celebrity Hiding in Her Audience
Sandra Bullock & Blake Shelton Play '5 Second Rule'
Sandra Bullock & Blake Shelton Play '5 Second Rule'
Jessica Biel's Diet - The Graham Norton Show - Series 10 Episode 6 - BBC One
Jessica Biel's Diet - The Graham Norton Show - Series 10 Episode 6 - BBC One
Name That Song Challenge with Miley Cyrus
Name That Song Challenge with Miley Cyrus
Jimmy Kimmel Tells His Daughter He Ate All Her Halloween Candy
Jimmy Kimmel Tells His Daughter He Ate All Her Halloween Candy
Ryan Reynolds Has Had Enough of 'Frozen'
Ryan Reynolds Has Had Enough of 'Frozen'
Pete Davidson Got Stuck Paying for Kid Cudi's Birthday Dinner When Kanye West Crashed
Pete Davidson Got Stuck Paying for Kid Cudi's Birthday Dinner When Kanye West Crashed
Kevin Hart Spills on Jay Z (Late Night with Jimmy Fallon)
Kevin Hart Spills on Jay Z (Late Night with Jimmy Fallon)
Ellen and Jessica Biel Surprise Justin Timberlake!
Ellen and Jessica Biel Surprise Justin Timberlake!
Jimmy and Kim Kardashian West Freak Out Touching Mystery Objects
Jimmy and Kim Kardashian West Freak Out Touching Mystery Objects
Chrissy Teigen Doesn't Know Jack About John Legend
Chrissy Teigen Doesn't Know Jack About John Legend
Wheel of Musical Impressions with Céline Dion
Wheel of Musical Impressions with Céline Dion
Best Friends Challenge with Justin Timberlake
Best Friends Challenge with Justin Timberlake
Box of Lies with Chris Pratt
Box of Lies with Chris Pratt
Justin Timberlake Woke Up to a Wet Surprise from His Son
Justin Timberlake Woke Up to a Wet Surprise from His Son
Pictionary with Kristen Bell, Steve Harvey and Demi Lovato - Part 1
Pictionary with Kristen Bell, Steve Harvey and Demi Lovato - Part 1
One Word Songs with Rita Ora
One Word Songs with Rita Ora
Emma Stone Takes Buzzfeed's
Emma Stone Takes Buzzfeed's "Which Spice Girl Are You?" Quiz
Ellen Celebrates Her 2,000th Show with Surprise Guests!
Ellen Celebrates Her 2,000th Show with Surprise Guests!
Pour It Out with Chrissy Teigen
Pour It Out with Chrissy Teigen
Box of Lies with John Cena
Box of Lies with John Cena
Christoph Waltz Gives Jimmy Fallon a German Words Quiz
Christoph Waltz Gives Jimmy Fallon a German Words Quiz
Nick Jonas and Priyanka Chopra Made Their Own Couple Nickname
Nick Jonas and Priyanka Chopra Made Their Own Couple Nickname
Best Friends Challenge with Mark Ruffalo
Best Friends Challenge with Mark Ruffalo
Mad Lib Theater with Tom Cruise (Mission: Impossible Edition)
Mad Lib Theater with Tom Cruise (Mission: Impossible Edition)
Bradley Cooper Leaves with Jimmy Mid-Interview to Check if He's Wearing a Repeat Suit
Bradley Cooper Leaves with Jimmy Mid-Interview to Check if He's Wearing a Repeat Suit
The Whisper Challenge with Margot Robbie
The Whisper Challenge with Margot Robbie
Charades with Jessica Biel, Matt Bomer and Kelsea Ballerini
Charades with Jessica Biel, Matt Bomer and Kelsea Ballerini
What's Behind Me? with Tina Fey
What's Behind Me? with Tina Fey
Justin Timberlake Recaps the Christmas SNL with Jimmy
Justin Timberlake Recaps the Christmas SNL with Jimmy
One Word Songs with Meghan Trainor
One Word Songs with Meghan Trainor
Water War with Jason Momoa
Water War with Jason Momoa
Charades with Gal Gadot and Patty Jenkins
Charades with Gal Gadot and Patty Jenkins
Pour It Out with Margot Robbie
Pour It Out with Margot Robbie
Justin Timberlake Has a Silent Interview with Jimmy Fallon
Justin Timberlake Has a Silent Interview with Jimmy Fallon
Best Friends Challenge with Demi Lovato
Best Friends Challenge with Demi Lovato
Mad Lib Theater with Benedict Cumberbatch
Mad Lib Theater with Benedict Cumberbatch
Name That Song Challenge with Pharrell Williams
Name That Song Challenge with Pharrell Williams
Bradley Cooper and Jimmy Can't Stop Laughing (Extended Version)
Bradley Cooper and Jimmy Can't Stop Laughing (Extended Version)
Best Friends Challenge with Ariana Grande
Best Friends Challenge with Ariana Grande
Jessica Biel Talks Smack About Her Two Year Old
Jessica Biel Talks Smack About Her Two Year Old
Name That Song Challenge with Blake Lively, Carrie Underwood and Henry Golding
Name That Song Challenge with Blake Lively, Carrie Underwood and Henry Golding
Lip Sync Battle with Tiffany Haddish
Lip Sync Battle with Tiffany Haddish
Priyanka Chopra Jonas on Taking Nick Jonas' Name and Married Life as
Priyanka Chopra Jonas on Taking Nick Jonas' Name and Married Life as "Prick"
Kate Beckinsale Reenacts the Serendipity Elevator Scene
Kate Beckinsale Reenacts the Serendipity Elevator Scene