Lest you think Microsoft has no sense of humor, Microsoft's Sysinternals has released a Blue Screen of Death screensaver. Install it on your friend's computer to play a practical joke, or just use it laugh in the face of a catastrophic system crash.
Admittedly, I was a little scared when I first loaded it up since it does look real. Especially with the monitor problems
I've had recently.Blue Screen Screensaver