Birkenshock burr-Kin-sok noun 1. The ability of of a person who dresses unconventionally to resist abuse. 2. A feeling of disbelief when confronted with how you used to dress. "Whoah, grandpa... Hope you got your birkenshocks on because I just found one of you in a muumuu!" -Randall, who is not my grandson and does not appreciate the versatility and comfort of Hawaiian apparel and is no longer welcome to come over for cookies.