Manguangua means that something is really easy or made without any considerable effort. Often to refer to someone doing something the easy way because they're lazy.
"Quieren hacerunas elecciones con los principales candidatos inhabilitados. Que manguangua vale."
A Mangan originates from the word Mangan, from the famous member of St.helens england who preformed this position, the mangang consist's of 4 people, 3 men line up on there hands and knees side by side, then the female takes the middle man with a strap on dildo, and the other 2 men either side get a fist consisting on witch side there on deep in there ass's