Two guys are out in the woods hiking.
All of a sudden, a bear starts chasing them. They climb a tree, but the bear starts climbing up the tree after them.
The first guy gets his sneakers out of his knapsack and starts putting them on.
The second guy says, "What are you doing?"
The first guy says, "I figure when the bear gets too close, we'll have to jump down and make a run for it."
The second guy says, "Are you crazy? You can't outrun a bear"!
The first guy says, "I don't have to outrun the bear. I only have to outrun you."