What is the difference between ‘New York minute' and ‘Facebook minute'?

A ‘New York minute' is a very short period of time; it is actually less than a minute. The relatively new expression ‘Facebook minute' means the exact opposite. It is used to refer to a relatively lengthy period of time. Very often people say they will check their messages on Facebook and get back to you in a minute. Once they log in, they forget about their promise, and stay online for a long period of time.