Girls get frills. What do boys get?

I'm due in about two months with my second, a baby boy. My first is a girl and I've had a lot of fun sewing things for her - there are many amazing patterns out there I've found so far! But I've been thinking: I add frills to something and it's automatically "girly". Is there something you add to boys clothes in the same vein that makes it "boy-y"?

Bonus: I'd love to see your favourite boys patterns that aren't just a button up shirt with a fun fabric choice!