Justin Timberlake & Jimmy Fallon Test Their Friendship, Sing 'Ironic' and Throw Pizza Party on 'Tonight Show'

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When Justin Timberlake and Jimmy Fallon get together, the results are always entertaining.

The Trolls star
sat down with the Tonight Show host on Wednesday for a wild night of bromantic bestie fun that started with a flashback to their time at sleepaway camp as children.

Donning ridiculous wigs, fake braces and camp uniforms, Timberlake and Fallon shined with yet another installment of their signature sketch in which they play teenagers in the ‘90s, hanging out in their camp cabin after lights out.

This time around, the adorable besties passed the time by singing a hilarious rendition of Alanis Morissette's "Ironic," which is made all the funnier by their braces-induced slurring.

WATCH: Jimmy Fallon and Justin Timberlake Poke Fun at Their Epic Friendship

After the always-adorable sketch, the two sat down to talk about Timberlake's upcoming animated film, Trolls. But the singer couldn't help but mention how he stirred up a quasi-controversy recently at a voting booth.

After Fallon asked Timberlake what he's been up to, the 35-year-old artist replied, "Well, I recently voted. It was super quiet and under the radar."

On Monday, Timberlake voted in his hometown of Memphis, Tennessee. In a good-faith effort to encourage people to vote, the singer snapped a selfie while casting his ballot, which some believed was a violation of state election law. However, the Shelby County District Attorney's office later said they would not be investigating.

When asked if he had any advice for viewers when it came to voting, Timberlake looked directly into the camera to address those watching at home.

"Get out and vote," Timberlake said to a chorus of cheers from the audience. "But, uh, don't take a picture of yourself in there."

RELATED: Justin Timberlake Not Under Investigation for Taking a Selfie While Voting in Tennessee

The interview soon turned to Timberlake's work on Trolls, where he was an executive music producer, as well as a voice actor alongside co-stars Anna Kendrick, James Corden, Gwen Stefani and Zooey Deschanel.

"They asked me to produce the music and coach these 'actors' on how to sing," Timberlake said incredulously, "and I was like, 'All these people know how to sing, man.'"

"So, basically, I'm just taking credit for all of their genius," he added with a smile. "Thanks!"

However, there's no denying Timberlake's catchy contribution to the soundtrack, "Can't Stop the Feeling!" has taken the country by storm since he debuted it in May. But the hit single wouldn't have happened without a few important conditions.

NEWS: Justin Timberlake Proves Just How Adorable He Can Be While Talking 'Trolls' at Comic-Con

"If I wouldn't have taken this movie on, I never would have written this song, because we wrote it specifically for a scene in the movie," Timberlake shared.

"And also, if we wouldn't have had our son I never would have written a song like that," he added, referring to his 1-year-old son, Silas, whom he welcomed with wife Jessica Biel in April 2015.

"He's a good dude," Fallon said, smiling. "I like that guy."

As the interview came to an end, Fallon surprised his audience with a massive pizza party, bringing box upon box out on stage and allowing everyone to come up and eat a slice with the superstar besties.

WATCH: Justin Timberlake Says Son Is 'Everything,' Explains Why Jessica Biel Is Missing From 'Trolls' Music Video

Finally, the two put their friendship to the test by asking each other questions from Fallon's “Best Friends Box." The challenge, which is somewhat like the Newlywed Game, shined an interesting light on their relationship.

As it turns out, their preferred mode of transportation when hanging out together is a tandem bike (because of course it is), and Timberlake's favorite childhood sitcom was Cheers (not Gilmore Girls, which is what Fallon guessed, but Timberlake said it was a close second).

Finally, the game ended with them performing a duet of the song they "always end up singing together" when they hang out: "I'm Keeping Your Poop (In a Jar)" by Hayseed Dixie. Seriously.

However, not wanting to go out on that note, they closed the segment out with a sweeter duet of the 1982 hit "Africa" by Toto, and it was adorable.

Recently, ET caught up with Timberlake at the premiere of Trolls, where he opened up about how much his little boy already loves the movie and can recognize his daddy's character. Check out the video to hear more.

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