Knife nipples

When a male/female breast are super perky

Andrea has the sharpest knife nipples I have ever seen.

nipple knife

A nipple knife is when a females nipple gets really hard and could be used to cut open a potato or any other hard object a knife can handle.

Last night my girl friend had her nipple knife out cutting the potatoes and slinging them into the hot boiling water to turn them into mashed potatoes.