adj. When a group of people do something irrational just because everyone else is doing it, or because no one is doing something, or because some authority figure instructs people to do something irrational. Named after the famous experiment in obedience conducted by Stanley Milgram in the 1960's.
"I am starving, but I don't want to be the first person to hit the buffet table by myself."
"Dude, stop being so milgram."