When the gang views a tape from Barney's ex-girlfriend, everyone must share their most embarrassing moment in order to get him to tell the full story about the tape.
Ted and Robin are surprised to run into Barney when they volunteer at a homeless shelter on Thanksgiving.
When Ted attends his mother's wedding, he is disturbed by her overly affectionate relationship with her fiance.
Marshall bequeaths a "slap bet" slap to Ted and Robin; Lily's estranged father (Chris Elliott) visits for Thanksgiving.
Afraid they will never get pregnant, Lily and Marshall decide to see a specialist; Robin begins her new job.