As I mentioned before, I cheated. That said, check out Jude's 80's Skater look:
The hoodie is part adult sized sweatshirt (I plan to make a quick pair of pants from the remaining sleeves) and part sweatshirt fabric from Joann's. I used one of his existing hoodies as a pattern, but I skipped the zipper and just sewed in a triangle of ribbing so that I could pull it over his noggin. The "jams" are just a cropped version of these pants from Made.
I'm really happy with how this little outfit came out. There are, as always, improvements that could be made, but it fits and my little model seems to dig it. Check this sweet pose:
Hooray for kcwc and clothes that make you want to jump, jump!