Gifts for CS nerds

What kinds of gifts do CS majors like? I'm trying to find a gift for my friend but I'm not sure what his interests are. He doesn't like any of the things that nerds stereotypically like, like Star Wars and anime. He's autistic and spends most of his time coding. I think he's into hiking but he didn't seem too interested in hiking before I introduced him to it. Looking for anything under $40