coffin, a term meaning a thick pastry case for a pie

Far from lugubrious, a pie comprising coffin and filling was normal fare until the 16th century, when coffin was confined to its present meaning. 
It seems we have always put our valuables - be they meat, relatives or coins in coffers. We even keep our hearts in our chests. 
Samuel Whiskers and Anna Maria  simply merged the former and latter meanings of coffin when they prepared their roly-poly cat version.