Here's a common question that's probably been asked already, but go ahead and sate my curiosity anyway.
Say you're stranded on a desert island. Alone. Nothing but the waves and rocks and strange birds flying overhead for company. Hypothetically, what three important items are in your possession? Keep in mind they can be anything, except the tools necessary to, you know, do something useful like create a raft made out of buoyant rocks that conveniently floats you back home.
It's sort of like having a genie grant you three wishes, except under these barely described circumstances, you can't exactly wish your way out of the tight spot.
Think I'd have at least a five gallon tank of drinkable water, an umbrella in case it rained, and an extra pair of underwear. Because hey, if I get to plan ahead, I'm going to be practical about my three items.