Hold a giant kitkat at all times to bring the scale back down.
...however, unless you are hung like a horse - avoid putting those giant clown flappers near your willy when there is a lady about... it'll only make things appear smaller
Piano or Guitar, I'd go for guitar as your little finger looks longer than your thumb stretch.
I'm not sure that'd work. I have tiny, child-like hands and play both guitar and piano. This meat-fisted chap would be holding down three strings at a time!