a girlfriend of mine knit her son a "manly" scarf out of Alpaca wool, in his university colors (univ of Illinois, blue and orange). She did a totally random stripe pattern, and he LOVES it. Maybe you could try something like that? Just pick 2 or 3 colors that he likes, or that match his jacket, and go for it. I think ribbing is manly too, so you could just do 1 color, and that would add some not girly texture to it.