‘How I Met Your Mother’ Season 9 Spoilers: Slap Bet Ends With Marshall Giving Barney ‘Slap of A Million Exploding Suns’

"How I Met Your Mother" season 9 will return in January with an episode entirely dedicated to the end of the slap bet between Marshall and Barney. How will Marshall dole out the final slap? And what repercussions will it have on Barney's cheek? Find out in the latest "How I Met Your Mother" season 9 spoilers here!

The official synopsis of "How I Met Your Mother" season 9, episode 14, as reported by the Latino Post, reads: "In an attempt to deliver a devastating final slap to Barney, Marshall explains how he mastered the Slap of A Million Exploding Suns."

"How I Met Your Mother" series creators and executive producers, Carter Bays and Craig Thomas, revealed that the episode will occur entirely during a super slow-motion slap, with a musical guest making an appearance in the January 2014 episode, IB Times reports.

As we previously reported, TV Line noted that Jason Segel, who plays Marshall on "HIMYM" gave this spoiler about the final slap bet episode: "I'll just say two words, and you can take them any way you want: Hillary. Clinton."

We're not sure what that spoiler hint means, but we do know that Marshall's final slap will be so powerful, Barney's ancestors will feel it through the power of time-travel, Carter Matt reports. The website also adds that the episode will feature jokes about the lengths in which Marshall has gone to prepare for this big moment: doling out the final slap to Barney.

"How I Met Your Mother" season 9, episode 14, "Slapsgiving 3: Slappointment in Slapmarra," airs on Monday night, January 13, at 8 p.m. EST, when "HIMYM" returns to the CBS network after its winter break.