Ummm... Guitars make pretty sounds? That's about the extent of my guitar knowledge. That, and they're made of wood. (You can tell they're made of wood because you can build a bridge out of them.)*Ba-dum!*
By the way, it's not too late to give Robb a slightly-belated birthday present. All he wants is for you to go out and do something nice for somebody, just because. Exercise your whimsy!