Merriam Webster defines groupthink as:
a pattern of thought characterized by self-deception, forced manufacture of consent, and conformity to group values and ethics
A co-worker told me yesterday that this Friday night he'd be sleeping outside in a canyon with his eleven year old and his scout troop. He was given the choice of sleeping in a snow trench or a snow cave. Of course the kids think this is the greatest idea in the world but what adult proposed this to the group and how did they all agree?