Ink on Stink refers to women of lesser intelligence that believe a tattoo makes them more sexy, allows them to make a statement of some kind, or is just stylish. In reality it shows their lack of intelligence and vulnerability to an impulse to distort their body without a thought to future consequences. It makes them look slutty, which is where the Stink portion of this expression comes from, since sluts frequently have stinky vaginas. Ever see a woman with a tattoo she got years before that is now indistinguishable due to older sagging skin?