Ted and Robin are surprised to run into Barney when they volunteer at a homeless shelter on Thanksgiving.
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.
Lily's long-lost dad shows up unannounced on Thanksgiving Day. She confides the real reason she stopped speaking to him three years ago, as she and Marshall disagree on how they should deal with the dispute.
When Ted attends his mother's wedding, he is disturbed by her overly affectionate relationship with her fiance.
Barney declares February 13th a holiday for desperate women; Marshall receives a Valentine's Day surprise from Lily; Zoey and Ted work on figuring out their relationship.