expression, noun
utter confusion; chaos; pandemonium
Describes a situation where everything is turned upside down, with people running around in a panic or great excitement. Often used for large-scale disorder or frantic activity.
火事の知らせで、会社の中は上を下への大騒ぎになった。
With the news of the fire, the office was thrown into utter confusion.
突然の停電で、駅は上を下への大騒ぎだった。
Because of the sudden blackout, the station was in chaos.
A set phrase literally meaning 'a big uproar of up and down', i.e., everything turned upside down. The exact origin is uncertain, but it vividly depicts a scene of total disorder.