The term "shrink" is a slang term that originated in the mid-20th century as a derogatory term for therapists, particularly psychiatrists. There are several theories about the origins of the term, but it is generally believed that it refers to the idea that therapists "shrink" their patients' problems through therapy.
However, the term "shrink" is generally considered inappropriate and disrespectful in the mental health profession. It is important to use respectful and appropriate language when referring to mental health professionals and the work that they do.