(n) :
(U.S.)
notice of the
termination of
employment; (U.S.) the
title for an
automobile (source is most likely from California, where the title is printed on a smaller index-card sized piece of pink paper, as opposed to most other states where the title is typically a full-size 8 1/2" x 11" sheet, usually printed on blue or blue-green paper with borders, similar to a stock certificate)
"after 20 years of dedicated service to the firm, they simply handed him a pink slip one day."