“Write what you know” is all very well but it certainly does restrict most of us within narrow confines. You must also be able to write what you don’t know, but can imagine. This is what your imagination is for. Let it fly!
Using the first person, describe an event or action you are fairly sure you will never experience first hand. Be very specific – the more details you incorporate the more likely it is that your reader will believe you. Include your feelings and reactions.