Trama

Barney freaks out when Marshall bequeaths a "slap bet" slap to Ted and Robin. Meanwhile, Lily's estranged father shows up for Thanksgiving.

Marshall and Lily are hosting 2009 Thanksgiving at their new apartment for the first time. Because Ted and Robin come through with what Marshall deems the make or break item for Thanksgiving, he shows his ultimate gratitude: he is giving them the fourth of only five slaps to Barney Marshall won in a bet with Barney in 2006. The terms of Marshall's gift: it must be done before sundown so as not to interfere with dinner, Ted and Robin can decide between themselves who gets to deliver the slap, and they will tie Barney down to a chair for the slap. Barney, who has always hated the anticipation of the slap as much as the slap itself, is hoping that time will run out as Ted and Robin discuss then argue over who deserves to deliver the slap more. Thanksgiving may end up being as bad for Lily, whose deadbeat father Mickey Aldrin, who has always disappointed her and from who she has officially been estranged for three years, shows up at their doorstep. Marshall tries to convince Lily to forgive Mickey, whose appearance may not have been totally by accident.—Huggo

Future Ted describes the Thanksgiving of 2009, when Lily and Marshall invited the gang over to their apartment for dinner. Marshall had picked out a wonderful turkey, but had left it in the cab. Robin and Ted pick it up at the Port Authority, and in gratitude, Marshall bequeaths one of his slap bet slaps to them, on the condition they slap before sundown (so that it doesn't interfere with Lily's meal) and decide amongst themselves who gets to slap Barney. Barney will be tied to a chair, now called the slapping throne.

Lily's estranged father, Mickey (Chris Elliott) shows up. Mickey always wanted to invent the next big board game and had ignored Lily all through his and her life. Divorced from Lily's mother, Mickey had been living in his parents' (Lily's grandparents) basement, trying to develop his strange board game ideas (Tijuana Slumlord, Car Battery (how long can you hold on), clown demon under the bed, Dog Fight promoter) and taking advantage of his father's generosity who took his job back at the steel mill to support Mickey. Mother is Rita (Christina Pickles). Mickey's parents had to postpone moving to Florida due to this. Marshall describes the look he saw in Lily's eyes at that moment, calling it the "you're dead to me" look. She had used the look on other people for trivial reasons, but she had not spoken to or of her father for three years.

Marshall, who is used to a close-knit family (he teleconferences with them for Sunday dinner), tries to convince Lily to allow her father to have dinner with them (it's been 3 yrs since Lily has been ignoring him). She stubbornly refuses (she says her mom supported the house by working 2 jobs. Her dad only broke her heart every single day for 20 yrs), but Marshall invites him in anyway, only to see Lily walk out the door. As they sit and wait for Lily to return, they play one of Mickey's unsuccessful games, "Diseases." After a part of the game sprays lead paint and horse bile all over the turkey, Marshall kicks him out and looks for Lily.

He finds her at Mr. Park's (Charles Rahi Chun) bodega, a man she had given her "you're dead to me" look. While she waited at the counter, hoping to avoid Mr. Park, she found out that he had died, which makes her depressed. Realizing what it would mean if her father died without seeing him again, they return to have Thanksgiving dinner together, inadvertently upsetting Mr. Park's widow (when Lily says Mr Park literally meant nothing to her and still his death upset her a lot).

Meanwhile, Ted and Robin playfully argue about who should slap Barney, begging off the honor to each other, but quickly start arguing seriously since they both want to slap Barney. Barney tries to extend the argument (to pass the deadline of sundown), frightened of the prospect of being tied to a chair and slapped. Ted reveals that he was not OK with Robin sleeping with Barney. He says he is still in love with Robin. He was lying, so he could get to slap Barney.

Eventually, Robin gifts the slap to Ted, praising his growth since being left at the altar & losing his job. Ted gifts the slap to Robin, as closure to her relationship with Barney (some part of her deep down wants to slap Barney for the breakup). Robin gifts the slap to Mickey as a welcome to the gang. Mickey gifts the slap to Lily as an apology for his absentee parenting. Lily can't bring herself to slap Barney, and Marshall explains that he gave out the slap to bring everyone together. Marshall declares that there will be no slapping today. A nerve-wracked Barney is released from the chair, but before he can sit down to dinner, Marshall slaps him in the face proclaiming, "That's four!".

As a postscript, a commercial is shown of Mickey's new board game (from Aldrin Games unlimited), Slap Bet, recreating the gang's tradition of slaps as a family game.