How can i get pain killers from a doctor without sounding like a druggie?

Ok, so my back is killing me. Or kills me from time to time, Ill just all of a sudden get these spasms i guess and it feels like there's a ship sitting on my back and it happens when I'm sitting up or standing to the point i cant move and it just hurts like crap. I do a lot of lifting at UPS, I'm not saying that is the reason..I was wondering if i was to go to the doctor how can i get them to prescribe me lortabs, percocet, etc. and not those lame muscle relaxers without sounding like a junkie..Because I know unless I tell them what I want there just going to try and prescribe me stuff like naproxen, skelatin, etc..What is the most likely drug I could get for my back pain? What are the strongest muscle relaxers? And how do I go about asking a doctor to give me a specific drug without them thinking I'm just trying to abuse them?