(b)To get wasted (to shibby).
(c)An exclamation that one...exclaims when one finds something rediculously cool (works best when used in an dramatic, opera singer-like voice).
(b) Jesse- Dude, maybe we need to cut back on the shibbying.
(c) Chester- Dude, you just touched Christy Boner's hoo-hoos!
Jesse- Shibbyyyy! (Opera voice)