I'd advice to look into a simple but custom-made neck-chain (for example his name in gothic lettering or something along those lines) if you reckon he'd use it, some like it, some don't.

Or if you find tickets to a concert/show that he'd enjoy.

Something like that, I guess. I'm horrible at even finding out what gifts I'd want

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You know the world is going crazy when the best rapper is a white guy, the best golfer is a black guy,the tallest guy in the NBA is Chinese, the Swiss hold the America’s Cup, France is accusing the U.S. of arrogance, Germany doesn’t want to go to war, and the three most powerful men in America are named Bush, Dick, and Colon.
— Chris Rock