Solitaire in desert

A Scoutmaster was teaching his boy scouts about survival in the desert.

"What are the three most important things you should bring with you in case you get lost in the desert?" he asked. Several hands went up, and many important things were suggested such as food, matches, etc.

Then one little boy in the back eagerly raised his hand. "Yes, Timmy, what are the three most important things you would bring with you?" asked the Scoutmaster.

Timmy replied: "A compass, a canteen of water, and a deck of cards."

"Why's that Timmy?"

"Well," answered Timmy, "the compass is to find the right direction, the water is to prevent dehydration..."

"And what about the deck of cards?" asked the Scoutmaster impatiently.

"Well, Sir, as soon as you start playing Solitaire, someone is bound to come up behind you and say, 'Put that red nine on top of that black ten!'"