How I Met Your Mother
The mother of all slaps will be delivered in the midseason premiere of "How I Met Your Mother." CBS

“How I Met Your Mother” returns from its holiday hiatus on Monday, Jan. 13, with the highly anticipated third slap for Barney.

As the CBS sitcom prepares to end in March, “How I Met Your Mother” has started wrapping up all its loose ends … including the “Slapsgiving” saga. For those unfamiliar with “Slapsgiving,” the whole debacle began during Season 2’s “Slap Bet,” when Marshall and Barney made a bet, and the winner was allowed to hit the loser as hard as he possibly could. Barney ended up losing, and Marshall was granted five slaps to Barney, which could be doled out without a warning and without an expiration date. That number of slaps rose to eight for Marshall when Barney refused to wear the infamous “ducky tie.”

The season returns with Marshall having only slapped Barney six times -- once during “Slap Bet” in Season 2, once during “Stuff” in Season 2, once during “Slapsgiving” in Season 3, once during “Slapsgiving 2: Revenge of the Slap in Season 5 and twice during “Disaster Averted” in Season 7.

So, how will the final two slaps occur? Thanks to a leaked synopsis for episode 14, it appears as if Marshall has been working on something extra special for the soon-to-be groom. The synopsis reveals the following:

“In an attempt to deliver a devastating final slap to Barney, Marshall explains how he mastered the Slap of A Million Exploding Suns.”

While the plot description doesn’t reveal too much, “How I Met Your Mother” co-creator Craig Thomas took to Twitter to dish out some more scoop. According to Thomas, fans shouldn’t assume that Monday is the “final slap,” hinting that the two remaining slaps could be stretched past “Slapsgiving 3.”

Thomas also said that episode 14 is “perhaps the single strangest visual effect we’ve ever done on #HIMYM.” Could the “strangest visual effect” have anything to do with the exciting and long guest-star list for the episode? Besides a visit from Boyz II Men, it looks like Barney will be getting visits from some ex-lovers in episode 14.

Stacy Keibler will reprise her role as Karina, a bartender who Barney tricked into sleeping with him in Season 5, episode 12, “Girls Versus Suits.” Nazanin Boniadi will be returning as Nora, Barney’s ex-girlfriend and Robin’s co-worker at World Wide News. April Bowlby’s “Crazy Meg,” a clingy girl who Barney hooked up with, will also appear, along with Barney’s first girlfriend, Shannon (Katie Walder) and Lily’s co-worker, Shelly (Eva Amurri), whom Barney stole from Ted.

Episode 14 will air on CBS on Monday, Jan. 13, at 8 p.m. EST. What do you think will happen in the midseason premiere, “Slapsgiving 3: Slappointment in Slapmarra”? Let us know your thoughts in the comments section or send a tweet to @AmandaTVScoop.