Sunken in cheeks as a result of methamphetamine use. The first visible sign that a person uses methamphetamine due to loss of appetite and consequent loss of muscle tissue and fat in the face. The longer the use, the more pronounced the vertical indentation to the cheek. Eyes that appear to be "bugged" out, visible sores from picking at the skin, and loss of teeth develop after the appearance of Singleton cheeks.
It's obvious that guy is a meth addict, look at his Singleton cheeks.