When no one eats any more Oreos because the packaging prevents any more from being eaten, until someone else opens the packaging further, thus making everyone immediately want to eat Oreos once again. Also includes other snacks.
The same goes for those in college, when you are waiting to enter a class or leave a testing session. No one will enter/exit until someone else enters/exits first, thus starting the Oreo Effect.
*everyone playing a game on the television*
*after 5 minutes of no one consuming an Oreo, Jim, the least laziest, decides to tear open the package so three more rows of Oreos are accessible*
*Everyone in the same room as Jim now wants an Oreo all of the sudden, thus starting the Oreo Effect*
*Everyone sits outside of an empty classroom, watching the doorway.*
*Jim, the bold one, decides to enter the class immediately when he arrives*
*Everyone then decides they too want to enter the classroom after Jim, thus starting the Oreo Effect*
*Everyone sits with a finished test, waiting for someone else to leave*
*Jim, the bold one, decides to turn his in when he's done*
*Five or six people simultaneously turn their tests in, thus starting the Oreo Effect*