It's all bleedin' comin' together! Here's how to do it: Paint your nails in a coat of the darker of two polishes that you want to use. Once they're all dry, going nail by nail, quickly paint one side of the nail the original base color, and then the other side of a nail a contrasting color. While both halves are still wet, take a toothpick or needle and gently (like, barely any pressure) drag lines across the border between the two colors. Boom. Done. Easy peasy.