30 Rock (2006)

"Reunion," Season 3, Episode 5 Liz goes back for her 20-year high school reunion expecting to be pitied as the old nerd and discovers her classmates remember her as the mean one. Jack tags along and passes himself off as a missing classmate, Larry Braverman. The episode turns Liz's self-image inside out, which gives Fey some of her sharpest material, and Baldwin inventing a whole life on the spot is a reliable laugh on every rewatch.