secret squirrel

Etymology
From, a 1960s secret-agent cartoon character parodying.

Noun

 * 1)  Someone who is being secretive.
 * 2) * 2010, R. P. Nathan, The Second Best Man, Cassiopeia Publishing, page 46:
 * Christian was working on some Secret Squirrel project with Mike, and Wayne had his headphones in and was coding furiously.
 * Christian was working on some Secret Squirrel project with Mike, and Wayne had his headphones in and was coding furiously.