Here's a breakdown of its origins:
* "Josh" as a verb: The verb "josh" meaning to tease or joke first appeared in the early 1900s. It's likely derived from the Yiddish word "yosh," meaning "to joke."
* "Joshing" as an adjective: This usage further developed in the 1920s and 1930s, becoming a common slang term in the United States.
* "Joshing you": The phrase "joshing you" is simply a way of saying "I'm just teasing you," usually in a lighthearted and friendly manner.
While the exact origin of the word "josh" is uncertain, its connection to Yiddish and its rise in American slang during the early 20th century point to its likely origins in the immigrant communities of that era.