my brother is 15 and he loves geometric designs, he designed a quilt for me to do but I changed it to make it easier. You can see the design here
http://www.quiltingboard.com/t-136176-1.htm scroll down for what I did.
Another idea would be a rail fence, super easy too. But I think that just about any quilt could be made for a teen boy with boy colors and as long as it doesn't look like something for a young kid.
Or a simple denim rag quilt would work as well. Thrift stores have a lot of jeans at cheap prices too (some of the denim is really soft too! I should know, I work at one!) And you wouldn't have to worry about how it was washed as denim is pretty durable.