"but charcoal is white"

It's advice time, internets! Little brother is being dragged, I mean, is really looking forward to attending his first semi-formal. Oh, the joys of high school. I went over for dinner tonight (yay mashed potatoes) and somehow found myself offering to go shopping tomorrow with my brother and dad - a first - and being eagerly accepted. Dad is to advice on the purchasing of a masculine wardrobe. I'm to provide an eye for style. Right. Except I've never done more than walk through the men's clothing section.

What should he wear? We don't have any idea what his date is wearing, so I'm thinking neutral, yes? But the boy needs classy. I think charcoal grey trousers. Dad thinks a "sport coat," whatever that is. I'm thinking fun tie. Please throw out any tips, ideas, etc - and in exchange I promise a photo essay on the experience! This is going to be fun. I am going to die laughing if something else doesn't get me first.