Mexican Crease is when your dry-cleaners make a special crease to your dress shirts. Traditionally, they are western dress shirts that originated from the Mid-west and South; especially Texas. It is very popular with Vaqueros, and like minded individuals. The crease goes from the top shoulder to the wrist, and is parallel to the arm. It points like a teepee on the bottom and top.
It is preferred by many because it adds and extra “neatness” to the outfit.
That cowboy stud looked good - he was sporting a sexxy Mexican Crease.