Sometimes your nipples and rings may appear to float in the air (in the same spot) as your avie's body randomly moves about while standing.

This is due to the nipple rings being attached to incorrect attachment points (e.g. You selected Attach > chest ).* Due to the unfathomable way SL works, the correct attachment point for nipple attachments is the spine. 

To fix the problem, just re-wear the nipple rings to the spine. It will be rotated in some really weird position when you do that - just adjust them back and you should be fine.

* When you got a fresh set, choosing the default inventory wear will automatically attach to the spine, as that was the correct, default position. However, if you have manually selected any other attachment point, any subsequent wear commands will attach to that new attachment point.