Definition & Meaning of "window licker"in English

What is the origin of the term "window licker" and how is it used?

"Window licker" is a slang term for a person portrayed as intellectually disabled. It appeared in English in the late 20th century, based on the stereotype of individuals with severe cognitive impairments exhibiting behaviors such as licking or banging on windows. The term is used in informal, mocking, or insulting contexts, often online or in casual speech, to demean someone's intelligence or behavior. It is highly derogatory, offensive, and ableist, and never neutral.