When a lie is told in jest or a hyperbole is spoken - "everyone is in on it" - thus the shared lie or gross exaggeration becomes part of the psychology of the joke or story. A similar phenomenon occurs in the scenario of a "white lie". The consequences of being caught in these "little lies" are minimal - if anything at all. Moreover it is a fundamental nonverbal axiom that the ability to convincingly commit a deception is proportional to the ramifications of being caught.
With the above premise in mind, it is very interesting to note that recently at the Clinton Global Initiative event when Barack Obama said, "I was just discussing with [ear rub] President Clinton that if ah Chelsea begins delivery while I'm speaking - she has my motorcade and will be able to navigate traffic ..." he rubbed his right ear. This act demonstrates that the President is not a "good liar", for even in the context of a shared-joke his body language still betrays him.
Note also that the President's downward head-neck configuration and his prolonged eyelid closure add congruity and thus validity to this cluster-context of deception.
Nonverbal Communication Quiz-Analysis No. 2967: George Clooney & Amal Alamuddin Wed in Venice - All The World's a Stage - Sincerity level of Smiles
Nonverbal Communication Analysis No. 2946: Barack Obama's 10 September 2014 ISIS Speech - Body Language Tells
Nonverbal Communication Analysis No. 2807: Barack Obama at 2014 White House Correspondents' Dinner
Nonverbal Communication Analysis No. 2939: Barack Obama in Tallinn, Estonia
Nonverbal Communication Analysis No. 2745: Vladimir Putin Deception regarding Crimea
Nonverbal Communication Analysis # 1907: Governor Rick Scott tells a Lie
Nonverbal Communication Analysis No. 2701: Cuddling, Romance, Affection and Foot-Shunning
Dating & Romance Nonverbal Communication Secret # 1010: What Makes the Twinkle in Her Eye? - Rashida Jones