Warning: This sounds like one you've heard before but it's not.
A hunter leaves his camp and heads one mile north. Scanning the horizon for prey, he spots a likely spot to the east. He walks for a half mile before spotting movement further east. He sprints the half mile only to find that whatever was there is gone. Downtrodden, he walks the one mile south back to camp. Opening the door of the hut, he begins to call out for his partner when he sees it: A live bear in the hut! Thinking quickly, he pulls out his rifle and shoots it dead. Hearing the gunshot, his partner emerges from the other room. "Hey!" he shouts, "I just captured that bear outside and brought it in here to study!" Sheepishly, the hunter admits that he probably reacted too hastily.
How many legs did the bear have?