White person or US American citizen who trafficks drugs and negotiates with Mexican cartels.
The Mexican cartels sometimes use a cornerback (US born citizen)to traffic narcotics into America. Corners or cornerbacks are useful dealers because they live in the USA.
When you're playing a tactical video game like Fire Emblem or Advance Wars and one of your units gets stuck in a corner and literally cannot move anymore. Unit then usually dies from being attacked in multiple directions. Can also apply to games like Risk.
I had this sweettank in Advance Wars, but the AI totally cornerfucked me!