Plot: Lucy, Ricky, Fred and Ethel reminisce (via flashbacks of previous episodes) as they trim the tree on Christmas Eve. The flashbacks, all from season 2, include Lucy telling Ricky about her pregnancy in "Lucy Is Enceinte," Lucy, Ricky, Fred and Ethel singing in a barbershop quartet in "Lucy's Showbiz Swan Song," and Ricky, Fred and Ethel frantically preparing for Lucy's impending labor "Lucy Goes to The Hospital"