Here is my sentence.
First, I'm not sure what おしろ means, perhaps somewhat could inform me since Jisho and google translate are both giving results that I don't think are correct. I'm thinking it's some sort of slang.
Now for the main question. I believe the なんだ to be the explanatory の and this sentence means, "(The thing is) You ask for too much." What's the reasoning for taking the る off here? すぎ would be the stem of すぎる. Every example I've ever come across of explanatory の with a verb has not used the stem. What's the difference here?