Kicking and Screaming

Question: In the scene where Will Ferrell is talking to his wife he says "They were running around like whirling derbishes, and I don't even know what that is" or something to that effect. What is a derbish and why does it whirl?

Chosen answer: An actual dervish (not derbish) is a member of any of various Muslim ascetic orders, some of which perform whirling dances and vigorous chanting as acts of ecstatic devotion (hence the term "whirling dervish"), though in general 'a whirling dervish' is used for anyone who moves with an unfocused, almost frenzied energy.