[norwaypinesavage]

If you really want to mess with people, run your clock backward, leave off the numerals, and turn it on its side. (I did that for my clock in college. I’ll admit, though, that I had to do it one step at a time in order to be able to tell the time with a quick glance.)

[EEGator]

I like it. :)

[GingisK]

That will screw up your relationship with your spotter.

[bravo whiskey]

I have a binary clock set to 24H instead of 12H.