When your partner sucks on and bites your skin, the pressure breaks little blood vessels under the surface. Those broken vessels release tiny spots of blood called petechiae. A collection of these blood spots forms a larger dark spot, which is basically a bruise.

Are hickeys bad for you?

Is that true? No, hickeys don't cause cancer, and they aren't dangerous. A hickey is a bruise that forms when a person sucks and lightly bites an area on another person's body, causing the blood vessels under the skin to break. While some people enjoy giving or getting hickeys, other people may find them painful.

Why do I get random hickeys?

It forms when you or someone else -- a friend or partner -- sucks on your arm, neck, or anywhere else on your body. The pressure and suction break small blood vessels just under the surface of the skin. The blood that leaks out of those vessels leaves a telltale mark that others may comment on.