Why do Ghanaians say "Charlie"?

I was in the bus with other people, a friend mistakenly stepped on the toe of another. His first reaction was; "Charlie! Sorry".

I turned and asked, are you a Ghanaian? and the reply was just what was expected; yes.

Then I started Wondering, why do Ghanaians say Charlie at all times?. In my findings, I found out that Charlie, for Ghanaians is just like calling a friend, what some other people in other countries may say "guy" orany other name you use in reaching out to your paddies.