The Y2K bug strikes at the turning of the millenium. Many computers that are running the world do not recognize that the year after 1999 is actually 2000, rather than 1900. Those who designed the first computers were worried that their computers would eventually take over everything, including their jobs of designing computers, so they built in the Y2K bug. These same nerds were recruited out of early retirement and paid exorbitant fees to fix the problem that they caused.

The creators of the Macintosh did not feel like being called out of early retirement so they didn't bother with the Y2K Bug thing. It is not their fault that your phone company doesn't use Macintoshes.

Of course, nobody knows if Y2K will actually be an issue yet. Some people are stockpiling toilet paper while others blow their noses with total abandon. My personal theory is that the only machines that will truly be affected by the Y2K bug are time machines. This would explain why nobody has visited from the future to allay our concerns.