Front's okay; back is always horrid

Front's okay; back is always horrid

How do I tell hairdressers to cut the back of my hair like I want it (not like they want it)?  A combination of genetics and neck-wrangling auto accidents requires a short-as-a-man's haircut in the back or within hours, it is sticking straight out.  My neck is particularly short, too, and my face shape more pear than apple, so I need it short to offer lift and height, too. 

 I have some shave up two inches and straight across (they don't even want to know what I would do to them if *I* had the shears and they were sitting in front of me).  If the would even shape that so that it was graduated not only from the bottom but also from the rest of the hairline behind my ears, I could live with it (although shaved is NOT what I ask for except AT the hairline).  

Could someone offer me some hairdresser jargon that might help me explain better, perhaps?  I trust hairdressers less than felons nowadays.

Help!? :-)