Monkey-hunters use a box with an opening at the top, big enough for the monkey to slide its hand in. Inside the box are nuts. The monkey grabs the nuts and now its hand becomes a fist after which the monkey tries to get its hand out but realizes that the opening is big enough for the hand to slide in, but too small for the fist to come out. At this point, the monkey has a choice, either to let go of the nuts and be free forever or hang on to the nuts and get caught. Guess what it picks every time? You guessed right!. He hangs on to the nuts and gets caught.