Chris Christie is definitely not used to riding in the backseat. Last night in Florida, during Donald Trump's press conference/Super Tuesday victory speech, this became painfully evident.
The Governor of New Jersey exhibited many nonverbal faux pas while Mr. Trump was speaking - but the following one is particularly glaring.

Christie has "baggy skin" drooping down over his eyes/eyelids (from the region below the eyebrows and above the eyelids) - the medical term for this is "dermatochalasis" - it's very common and is not directly influencing his nonverbal behavior - yet it prevents most people from noticing the fact his upper eyelids (particularly on HIS left) are opened significantly wider than baseline. Having said that, most people can see there is something abnormal regarding his eyes and their gaze in this moment. This wider than baseline eyelid opening is secondary to Christie's increased adrenaline.
Chris Christie's mouth is configured in what is colloquially referred to as "Slack-Jawed". Body language novices will often confuse this with a mouth of surprise - yet it's not. Note that it's not widely opened - AND there are no visible teeth.
The slack-jawed nonverbal clustered with his widely opened eyelids together indicates emotional shock. Governor Christie knows he's been reduced to one of Trump's "yes men" and he's not been in such a position (to Trump or anyone) in many a year. His intellectual brain knows what is happening - however his emotional brain is having trouble fully grasping it.
See also:
Nonverbal Communication Analysis No. 3484: Chris Rock's Opening Monologue at the 2016 Oscars
Nonverbal Communication Analysis No. 3363: Chris Christie's Viral Video - Why do even Democrats love it?
Nonverbal Communication Analysis No. 2674: Did Chris Christie Orchestrate Bridge Closure or Cover Up His Subordinates Actions? Body Language Tells Us ....
Nonverbal Communication Analysis No. 3233: Chris Christie formally enters the 2016 Presidential Race
Nonverbal Communication Analysis No. 3109: Why Chris Christie Will Never Win The White House in 2016 (or the Republican Nomination)
Nonverbal Communication Analysis No. 3265: Donald Trump, Exaggerated Mouth Movements and Narcissistic, Hyper-Alpha Personalities
Nonverbal Communication Analysis No. 3384: Donald Trump Repeats Controversial 9/11 Claims
Nonverbal Communication Analysis No. 3436: Is Hillary Clinton Intimidated by Donald Trump?
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