Oddest (and coolest) thing to happen to me was when I was wandering some tunnel somewhere, and came face-to-face with one of those really powerful Super Mutants - the ones even more powerful than the Masters. I entered a door and quick-saved, but realised I was on little to no health, and almost near death, and the mutie fired a rocket at me just after I saved.
I must have pressed the wrong combination of buttons at the exact moment I was nose-o-nose with the rocket and the main menu came up. I loaded my game, but it loaded funny and the mutie and rocket were doing this hilarious little flailing movement, ragdolling about like kids on a sugar rush, and nothing hit me!