You have one (1) ordinary six-sided die (i.e., the traditionally marked, uniform-density, cubical kind that you could find in any Vegas casino within about 5 minutes).
You need to make a random choice between four (4) alternatives, same probability for each (25%, i.e., barring the occasional coin-landing-on-edge weirdness that supposedly can happen in real life, which we won't worry about).
You could, e.g., roll the die and if you don't get 1,2,3,or 4, just roll again and keep rolling until you do. That would be too easy, and also could conceivably take a while if you get unlucky with the 5s and 6s.
But the real problem
is that, due to various contrivances entirely beyond your control, it just so happens that if you roll the die a second time, you will be plagued by frogs, and (trust me on this) you really do not want to be plagued by frogs
So you absolutely have to do it in one (1) roll. Good luck.
Well okay, if that one was too hard, here's an easier one:
You're running a meeting and there are four people who want to speak. You need to randomly decide what order they go in and you want to be Completely and Utterly Fair about it ... meaning each of the (4!=24) possible permutations of the speakers has to be equally likely. Once again, you have one (1) six-sided die, and the frogs will only allow it to be rolled once. Good luck.