I pretty much always use "niner" and "fife" but I cannot bring myself to say "tree"
I was fortunate in that my father is a radio ham and I always used to listen in to the airband on a dodgy little radio he gave me when I was younger. This helped me a lot when I started my PPL. I already knew the jargon and the phonetic alphabet.
All seems quite funny when you do the RT practical, when everything is by the book and almost ridiculous sounding, then you hear ATC in the USA and it's frequently of the form...
"yeah...left, right, ground point niner"
