Prank - Change the terminal/konsole colour

This trick works wonders on those linuxers who love using terminal for most of their tasks. I am not proud to say this but actually someone played this trick on me . He just changed the terminal font colour to match my background colour. So, ultimately whenever I tried to open the terminal all I saw was this complete black window. At first I thought it was taking some time to load and even rebooted once. But eventually after trying a few commands at random I figured out the problem.

But honestly.. I am a great command line fan and I was completely clueless then (ya this was the exact expression)