The Juice

Jimmy Fallon and Stephen Colbert sing about their friendship on ‘Late Night’

NBC

We all know the saying “keep your friends close, but keep your enemies closer.” But when it comes to the pair of Jimmy Fallon and Stephen Colbert, it’s tough to tell if their ties are as friends or foes.

But on "Late Night with Jimmy Fallon" Thursday night, these two feuding funnymen buried the hatchet with -- what else? -- a duet at the piano.

“Ivory and ivory, I can tolerate you and you don’t mind me,” they sang in unison to the tune of the famous Paul McCartney and Stevie Wonder collaboration “Ebony and Ivory.” The song continued with, “If Rihanna and Chris Brown can be friendly, why can’t we?”

Watch Fallon and Colbert's duet below (song starts at 2:30)

Colbert pokes fun at Fallon for laughing at his own jokes, and Fallon accused Colbert’s ice cream as tasting like Al Roker’s Depends – reigniting a feud that began in 2011 over whose Ben & Jerry’s ice cream flavour was selling more. With the competition in a constant see-saw, it’s clear this is still a touchy subject.

See also: Michael Bublé teased on 'Late Night' for being Canadian

Things weren’t always so hostile between the two TV personalities. After their ice cream duel brought them face to face, they declared themselves BFFSMs – Best Friends For Six Months. They also used their time as chums for good, raising $26,000 for DonorsChoose.org to help needy students. To boot, they chose to celebrate the milestone with one of their favourite best-friend activities: an on-air musical performance. Colbert gave an intense rendition of Rebecca Black’s YouTube hit “Friday” with The Roots as his backing band.

But as soon as those six months were over, Colbert and Fallon began another six months as eternal enemies, in which jabs, jokes, and stealing each other’s show segments were fair game.

See also: Stephen Colbert says the new pope can't be Canadian

Now those six months of hatred are over as well, so 48-year-old Colbert and 38-year-old Fallon are at a crossroads over their true feelings. Thursday night, they seemingly decided that they consider each other “OK, I guess.”

“Ivory, ivory, two good friends we’ll someday be. Ivory, ivory, let’s agree to disagree,” they sang together as “Late Night with Jimmy Fallon” closed. Since this is one running joke without a six-month timeline, we’ll definitely see more of this dynamic duo.