Andy says...

A cocktail made by adding a splash of Cassis to a glass of Champagne

Named after Felix Kir, French politician, freedom fighter and former Mayor of Dijon (which of course is where Creme de Cassis originates from).  The original Kir mixture (Creme de Cassis and Bourgogne Aligote wine) was popularise by him at social functions whilst Mayor, and so the local people named the drink after the great man; eventually someone decided to swap the white wine for Champagne and this new drink was born.