That’s the time and date of this entry: 01:02:03 04/05/06.
An observation that only a geek would appreciate. Or a math teacher, which where I got it (thanks, David). But it is an event that occurs only once a century.
You could claim that it will happen twice – this afternoon would be the second time – but then you’d have to stick the am and pm stuff in there and that ruins the elegance of the whole trivial exercise.
If you’re willing to skip the traditional US order for writing dates, you can find a similar once-in-a-century occurrence on May 4th at 03:02:01 – 06 05 04 03 02 01.
If you’re really into sinister coincidences, you may want to hide somewhere on June 6th at 6:06:06 – 666 666.
And no, I didn’t stay up until 1am to create this post. That’s why they write software that can tell time. :-)