I've got an old file named HELPME.COM taken from my family's XT. My father pranked me with it for April Fools, 87 or 88 - he added it to the shutdown script that parked the hard drive. The complete phrase was "Help, somebody get me out of here, I'm trapped in this computer! Help, somebody!" It still works in DOSBOX, although you've got to turn the emulation speed way down - the program does use a timing calibration loop, but it doesn't handle the massive changes in instruction timings since then.