riot act

Translations
предупреждение о недопустимом поведении
The teacher read the riot act to the noisy class.
Учитель сделал предупреждение шумному классу.
Definitions
The term 'riot act' refers to a law or a warning issued to prevent or disperse a riot or violent disturbance. It can also be used metaphorically to describe a stern reprimand or warning given to someone to correct their behavior.
Words
riot

noun
беспорядки
act

noun
акт