Colleen joins John and his Air Force buddies for his annual tradition of dirty Christmas caroling. Also, Joan tries to hijack Lark's first Christmas from Jen and Greg, Samantha gets lice from a mall Santa, and Tyler announces his plans for college.
- Colin Hanks as Greg Short
- Betsy Brandt as Heather (Short) Hughes
- Thomas Sadoski as Matthew "Matt" Short
- Zoe Lister-Jones as Jennifer "Jen" Collins-Short
- Dan Bakkeddahl as Dr. Timothy "Tim" Hughes, M.D.
- Angelique Cabral as Colleen Brandon Ortega
- Niall Cunningham as Tyler Hughes
- Holly Barrett as Samantha "Sam" Hughes
- Giselle Eisenberg as Sophia Hughes
- James Brolin as John Bertram Short
- Dianne Wiest as Dr. Joan (Pirkle) Short
- Hunter King as Clementine
- Sean Poolman as Darryl
- Donovan Scott as Santa
- Bella Shepard as Lexie
- Matt describes John and his friends caroling as "'Cocoon' meets 'The Hangover'."