A mantrum is a tantrum which, quite similar to a
small child, is when a man (who thinks he's
intimidating but is really just really fat and completely
arrogant) doesn't get his way.
Not unlike a child who has a tantrum over spilt milk, a mantrum is when a grown adult cries over a vehicle that was lost because of repossession because he doesn't pay the note, or when a man cries because his wife left him for a woman. It's when a grown man is being weepy because he's
lost control over
everything he's fought so hard to control and feels it necessary to cry
on the floor, like a bitty child in the market, to get his way.