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.
A singleton is the name associated with women that only have one nipple. The name originated from England, when a girl by the name of "Singleton", who was later found to be mentally challenged, was found running down a busy motorway completely naked. The most distinguishing feature of the crazed girl was the fact that she had a large right breast and a "deflated" left which did not show any form of nipple. Thus, the term "Singleton" was born.