ringing

I know there is already a Happy New Year thread but I feel like I need to drop a load on your guys. This year, quite possibly, has been the worst one I've experienced thus far, but that is most likely to be expected in an adolescent male. Going in order, I started the year with that relationship...

Whenever I pickup my bass and plugin there is a really high pitched ring. If i turn the volume off of the bass the ring goes away. It only happens when i'm not touching any metal on the bass (strings, pups, bridge) But If I touch any of those the ringing stops. Does anyone know how...