Some customers use neodymium magnets to create earrings that clamp over the earlobe, not requiring a piercing.  Small discs can work this way, but avoid magnets that are too large.  We find that anything much stronger than a pair of D21 disc magnets might be a little too strong -- left on too long, larger magnets can start to hurt.  Experiment with a few sizes, especially magnets with a listed pull force less than 0.5 lb.  Examples include D201, D201-N52, D21, D21B-N52, D301, and D301-N52.
People with a nickel allergy should avoid long exposure of nickel plated magnets against their skin.