I have an image in my head of him practicing that menacing look in the mirror in preparation for his mugshot.

Sorry dufus. You don't look menacing. You just look like a pathetic weakling trying to look tough.

Here on Agnostic a couple of days ago someone called tRump's expression a Kubrick Stare. (Sorry I don't remember who it was).

The term refers to an attempt to be intimidating using a lowered, forward thrust brow. It comes from the expressions often used in Stanley Kubrick films to portray unhinged, crazy, intimidating characters as Nicholson in The Shining or McDowell in A Clockwork Orange.

The idea of course predates Kubrick. A Google search turned up a site called TV Tropes that describes the 'Kubrick Stare' well --
'In chess, or in any type of competitive game, the Kubrick Stare is a common tactic used by players to intimidate, annoy, confuse, or discomfort their opponents. Mikhail Tal , the Eighth World Chess Champion, was a chess player well known for his stares.'

I think tRump's mind is stuck in the grade school mentality represented by these simplistic intimidation games. I'll be very glad when we're rid of him.