In one of his stand-up routines Jerry Seinfeld spoke about the anxieties of buying milk. When you walk the aisles of the supermarket you wonder which carton is the freshest (sell-by dates are always confusing). You wonder if you actually need another carton of milk.  You wonder if you are buying milk just because society tells you to buy milk. Its all too confusing. Ko Yang has created a milk carton that changes colour to indicate how fresh it is. When the colour of the carton has completely changed you know that the milk has expired.