Brass balls, of course. We imagine Richards is one of those "guys who have everything," but we're willing to bet this is his first pair of brass balls. And rather than just stick them on the shelf next to his Lifetime Achievement Award Grammy, we've thought of five better things Richards can do with his new balls.
Hang them from the bumper of the Rolling Stones' tour bus. In America, nothing says "I'm a douche bag" like having a pair of fake testicles dangling from your Ford F-150. But on the Stones' bus, such appendages simply scream, "I'm a huge rock star, bitches."
Add them to Johnny Depp's Captain Jack Sparrow costume. Depp based his portrayal of Sparrow on Richards, so why not add Richards' brass balls to the costume? They'd probably make really groovy earrings.
Donate them to Siegfried and Roy. This duo sports unbelievably big bulges in their leather pants, probably the result of stuffing with socks or something. The illusion would be much more convincing if Siegfried and Roy put Richards' balls in their undies.
Auction them off to charity. Because a signed pair of Keith Richards balls could raise a shit ton of money to battle testicular cancer or something.