I don't have the money for jewelry, so instead, I grow my nails out to about 1/8", file them to slightly rounded points, and paint them black.
Slightly rounded, so it's harder to hurt myself. They still hurt, it just requires a bit of pressure.
I use them to scratch people. My Aikido instructor asked me to clip them because they're a weapon, and if I scratch someone with them, the wound might get infected because of the bacteria. He says this as if it's a bad thing.