It is one way to do so, german youth also use several english terms or “Digga” which is a modified form of the word “Dicker” meaning fat. Although I am no linguist I would assume that Alter and Dicker were used in combination with Freund (friend) first since those are valid phrases that still are in use.

As much as English speakers call each other “male sibling” or “canine”.

Technically correct, but no one makes that association in everyday language.