"Shivery bite" is an expression used to describe a little something to eat after a dook(swim) in the sea. It was usually a biscuit or chocolate bar or maybe a packet of crisps. I first heard it when I moved to the East Neuk of Fife in the early 1960's. Children were hardy souls in those days and everyone used to swim in the outdoor sea-water swimming pools which still existed in Cellardyke, Anstruther and Pittenweem as well as in many other coastal towns and villages. The water was usually freezing even in the summer, hence the need for something to stop you shivering when you emerged blue with cold... I don't know if it's used so much nowadays but it's a great expression all the same!