As Insane Donald Trump said:... he eats shit because "at least he know what's in it."
Every little kid has tried it's own poop and after first trial as a rule would find that this is not a box of chocolates but not insane Donald Trump.
If gasoline is car's source of power, for Donald eating shit is fuel to keep him going, which explains why he is full of it.
Donald's favorite Mexican dish - Shitatos.