The first band I gigged with professionally was a jazz piano trio. I was only about fourteen, but the piano player seemed really old to me, probably only in his forties or fifties.
He used to use words like "Cool", "Groovy", "Hep Cat" and "Hot" all the time. I remember him telling me that I should not use my name "Jonathan", but call myself "Johhny" when we were gigging, as it made me sound cool..
The bass player and I used to giggle about it at the time, but, looking back, he was one of the coolest people that I have ever met. He was also one of the finest musicians with whom I have ever played, and taught me more about feel, swing and "Groove" than any other. Because of him, I got to jam with Barney Kessel. He was cool, dude..
Edited for a missing comma