See Steve Martin, Martin Short Play 'Best Friends Challenge' on 'Fallon'

"You're America's dad," Short tells Fallon, "and that certainly worked out for Cosby, so it should be fine for you."

Steve Martin and Martin Short cemented their comedic bond with insults during a hilarious "Best Friends Challenge" on 'The Tonight Show.'

Steve Martin and Martin Short cemented their comedic and personal bond with one-liner insults during a hilarious "Best Friends Challenge" on Thursday's Tonight Show.

Jimmy Fallon described the bit as "The Newlywed Game but for friends," asking the comedy legends questions that they answered privately on pieces of paper. "If [Short] won the lottery, what would he buy?" the host asked, and Martin fired back, "Friends." Short, meanwhile, roasted himself: "Another facelift but this time with a real doctor."

Later, asked which liquid Martin would choose to be, his teammate cracked, "Skim milk because he looks like a glass of skim milk." Martin asked, "Why would I want to be a liquid?" They also shared two of Martin's most embarrassing moments: "He slapped Barry Manilow because he thought it was me!" Short recalled, with Martin admitting, "Got confused in a men's room and dried my hands on the man next to me."

It took them the entire game to get in-sync and respond with the same answer. Prompted to "complete this sentence: Steve has the world's biggest blank," the comics both replied, "Collection of Nazi memorabilia."

Elsewhere during their interview with Fallon, the touring partners unleashed a spree of zingers while promoting their upcoming Netflix comedy special, Steve Martin and Martin Short: An Evening You Will Forget For The Rest Of Your Life, out May 25th.

First, after revealing a photo from their last Tonight Show appearance of the duo sitting awkwardly close on the couch, Short cracked, "We're as close as Kanye and Trump!" After Fallon gushed that the duo are "two of [his] comedy idols," Martin replied, "We are this close to following you on Twitter." Then Short's attempt at complimenting Fallon went haywire: "You're America's dad," he said. "And that certainly worked out for Cosby, so it should be fine for you."