Half-Life: Opposing Force Easter Egg - Computer Crashes

To see this one, start playing OpFor. When you're in the first level after the cinematic, get your power vest and then meet up with Otis, the fat security guard. While he's jabbering away, go up to the Windows computer in the room and "use" it. Try this about 2 or 3 more times; you'll see the infamous bluescreen!