Slapsgiving 2: Revenge of the Slap
How I Met Your Mother Season 5 Episode 9 (11/23/09)
It's Thanksgiving and Marshall found the perfect Turkey... until he leaves it in the cab that takes off. He's depressed until Robin and Ted show up with the turkey... they went to pick it up for the port authority. To say thank you, Marshall bequeaths slap four over to Robin and Ted.
Meanwhile, Marshall decides in the spirit of Thanksgiving to reunite Lily with her estranged father that she considered dead to her. Why? Because the mooch has spent his life trying to make board games and never got a real job and forced her grandparents out of retirement back to work so he could live with them. Marshall doesn't care and invites him anyway only to have Lily leave when he arrives. Lily goes to visit the cafe where she declared the owner dead to her since it's the only place open. It turns out the owner really is dead and it makes Lily realize how she would feel if her father actually died. She heads back upstairs and Thanksgiving and the slaps can begin.
Ted and Robin bicker over who can use the slap and eventually decide neither of them can do it. They even try and get Mickey and Lily to do it, but no one can. Marshall gets up from his chair he's tied to, thinking he's safe, only to have slap four used on him by Marshall.