A domestic car or truck such as a Chevrolet Silverado, Tahoe, Suburban, or Impala that has impractical junk installed like 20+ inch rims, billet grill, emblems removed, chrome trim that doesn't match factory appearance, euro tailights, blue HID headlamps, custom exhausts, lowered ride height, and dark tint. Often it would be having other car problems apart from "looking fly". For Imports like Honda Civic, it would be lowered, have a custom muffler, euro tailights, and aftermarket racing wheels. Usually the driver of these type of vehicles would be of a Mexican descent, hence the termed "Mexicaned".
You see that debadged Chevy Tahoe with those big rims, euro lights, and blue HIDs? It's been Mexicaned!