What was the secret service code name for JFK and Jacqueline Kennedy?
Former President John F. Kennedy was called Lancer, which was fitting for the so-called Camelot theme of his administration. His wife was called Lace. Their children Caroline and John Jr. were named Lyric and Lark respectively. His mother was referred to as Coppertone, and the president's youngest brother was Sunburn.
Code names have been always used by the US Secret Service to ensure the safety of the Presidential family. Anyway, nowadays, when all electronic communications are encrypted, they usually use the names just for briefness and to hold up traditions. All the Presidential family members' code names usually begin with the same letter.