What is ain t nothing but a thang?

"Ain't nothing but a thang" is a colloquial phrase that means "it's not a big deal" or "it's nothing to worry about." The phrase was popularized in the Southern United States and is often used in casual conversation. It can be seen as a dismissive statement to acknowledge that something is not significant or worthy of attention. The phrase has also been used in pop culture, including music and movies.