As Lily and Marshall host their first Thanksgiving as a married couple, Barney is tortured by the tick-tock of the slap bet countdown clock and the uncertainty of the exact moment the slap is going to be delivered.

When the gang finds out that Ted is taking his doctor on a date, they try to convince him, through examples of their own toxic experiences, why it's never a good idea to get into a relationship with someone you see on a regular basis.