Acting Unnatural

In fiction (comedic works especially), if a character is told to "act natural" to avoid drawing attention to what is supposed to be a covert task, there's a good chance they'll overdo it. Common flubs include reading a book upside down or Not So Innocent Whistling. May be related to the Centipede's Dilemma, where a conscious attempt to do something is inexplicably harder than doing it unconsciously. Unrelated to Not Himself.