The lunatics have taken over the asylum saying
Said of a state of affairs in which those in a position of control or authority lack the ability to fulfill their responsibilities, and should rather be examined.
With the teacher giving those students complete control over the classrom, it looks like the lunatics have taken over the asylum.
It seems as though the lunatics have taken over the asylum; otherwise, things couldn't have been so chaotic.
The term appears to have been first used in 1919, when the four most powerful figures in the American film industry—Charlie Chaplin, Douglas Fairbanks, Mary Pickford, and D.W. Griffith—decided to found their own distribution company, called United Artists. In response the producer Richard Rowland remarked, “The lunatics have taken over the asylum.” The remark got wide publicity and entered the language, subsequently applied to many other situations of a comparable nature and becoming a cliché.
Said of one who directly takes charge of numerous duties including vital or small daily tasks within an organization
She opened the local hotpot restaurant and called herself as the chief cook and bottle washer.