The /fnord command echoes "Nothing to see here." in text of the same color as the background. This is an Easter Egg.
As of version 7.0, the text is the default color of the font due to the internal background/foreground color check that ensures the color of the text is not mistakenly set as the color of the background. The bug was fixed in mIRC 7.21.
The above example is the equivalent of the following echo command:
//echo -aeq $+($chr(3),$color(background),$chr(44),$color(background),Nothing to see here.) Nothing to see here.
Added: mIRC 6.3