from Wiktionary, Creative Commons Attribution/Share-Alike License
- interj. okay; a humorous and light-hearted nonsense phrase indicating approval or mild excitement
- interj. wow; "that's remarkable" or "great"
Originated in America during the late 1960s. Hits of acid, ludes, and ecstacy were dubbed "cool beans" for their bean-like shape. They were also referred to as "whacky beans" or just "beans." On top of that, there is the homophone connection between the food "chili beans" and "chilly beans", literally meaning "cold beans". (Can we verify(+) this etymology?) (Wiktionary)