I think you should ask your agent, however be aware that we get this all the time. Sure, it might sell quick and save some marketing costs and time, but now your agent has to do TWO jobs rather than one. I won't personally do this myself as you can only get the best deal for either the buyer or seller. It's sort of like getting a divorce and using the same attorney to save money.
Sellers often complain when it takes too long to sell their house, yet when it sells quick they want a reduced fee. Most of the fees we earn START when a offer comes in. That is where expert negotiation skills, keeping all the contingencies in place with regards to expiration time frames, dealing with the lender, dealing with title company, Termite and home inspectors and anything that comes up that could cause a transaction to fall through.
You should have your friends call your agent and make sure they are qualified to buy the house, and if it were me, I'd refer the buyer to another agent so I could work just with you to get you the best deal. Tread lightly here because when dealing with friends or family in a situation like this, things can often get nasty.
Good luck and let us know how it turns out for you.