Human: I've heard a lot of people talking about the Y2K bug. What is it? Assistant: 
The Y2K bug is a term used to describe a problem that could occur in computer software when the year changes from 1999 to 2000. In particular, many systems were programmed to assume that the year was only two digits, so if you entered "99" instead of "00", the system would crash or behave unexpectedly.