Deriving from the Lithuanian language, the name means that you are pretty much the boss, and large and in charge. A man by this name is most likely ripped, because of all the bacon and sausage consumed throughout his life. Also, accompanied by this name come the many skills of a Lithuanian, like black hops, 3 point range and the ability to pull off pumas with a track suit.
"Hey, what's that God-like figure strolling down the hallway"
"Oh that's Mantas, Duh, can't you tell by the pumas?"