The Secret Service code names used by 12 presidents and first ladies — and the stories behind them

A Secret Service agent stands guard as US President Barack Obama answers questions during a town hall event at Benedict College in Columbia, South Carolina, March 6, 2015.

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• First families get their Secret Service code names at the very beginning of a presidential campaign.
• Presidents get to choose from a list provided by the White House Communications Agency.
• The code names are for security purposes, but they often get leaked or are overheard at events.