A native or inhabitant of the West Coast, most notably from California, Oregon and Washington. A backformation from the phrase "West Coast best coast" or West Coast is the best coast
with the suffix -er denoting, when added to a proper noun, the demonym, i.e. a person or inhabitant of said proper noun.
While Southerners might stress the first syllable of the word 'persimmon,' us Bestcoasters stress the second syllable.