Commandment #2 of the Ten Commandments of Il Culto del Caffe.
Thou shalt not muck around with coffee. Requesting a mint frappuccino in Italy is like asking for a single-malt whisky and lemonade with a swizzle stick in a Glasgow pub. There are but one or two regional exceptions that have the blessing of the general coffee synod. In Naples, you can order un caffe alla nocciola – a frothy espresso with hazelnut cream. In Milan, impress the locals by asking for un marocchino, a sort of upside-down cappuccino, served in a small glass and sprinkled with cocoa powder, hit with a blob of frothed milk, then spiked with a shot of espresso.