In BSD robots (which I’ve played since my early teens—we had a Windows port of “Daleks”—and never really figured out), I’ve always wondered if you can teleport into trash heaps (and accidentally telefrag yourself that way). Checking the source code just now, it turns out you not only can’t, you also can’t teleport into a robot! However, the robots move after you teleport so when you die after porting, that’s because you landed right next to a robot.