Future Ted tells us about how Marshall found the perfect turkey but lost it in his cab. Ted and Robin retrieve it from Port Authority. Marshall says that he is so thankful that he transfers one slap to them. Everyone agreed it was going to be the best Thanksgiving ever when suddenly Lily's father showed up - she hadn't spoken with him in years.
Apparently Lily's father spent years trying to invent the perfect board game. Lily's fallout with her father started when his poor financial planning caused him to have to move back in with his parents and force his father back to work. Lily declared him dead to her. In the present, Lily tells Marshall to get rid of her father and he tells him to hang in there.
Marshall tells Lily that it has been three years and that it was enough. He reminds her of all the times that he supported her pushing people out of her lives and she says that he was horrible for twenty years. She feels that he is taking her father's side. He tells her all the positive things that her father is doing and she wonders how he knows it. It comes out that Marshall invited her father. He says that since they are married, he is his family as well so he invites her father in and she leaves.
Robin and Ted argue over who will slap Barney. It goes on for so long that Ted even says that he still loves her just to get to slap him. The argument goes on until Ted realizes that the slap is dividing them. Robin tells Ted that he can have the slap and then Barney ribs her but then part of the game Lily's father brought explodes all over the turkey. Marshall kicks her father out and he goes to find her. She tells him that she found out one of the people that she declared dead to her actually died.
Robin and Ted argue again over who gets to slap Barney and it ends up going to Lily's father, who gives it to Lily, who ends up giving it up. Marshall says that there will be no slap since they really understood the spirit of the slap and then really hits Barney hard. Lily's father ends up making a board game based on the Slap bet.