This trick is completely useless but could be fun. You can write different words near the clock on the notification area.
1. Go to Start -> Control Panel and double click on Regional and Language Options.
2. Click on the ‘Customize this format’ button, Go to Time tab.
3. Enter the character or symbols you want in the AM / PM fields. But remember the maximum length is to 12 characters. Click OK.
4. After the ‘customization’ the notification area could look like this: