More properley "Kirkby Kiss" (named after the charming village of Kirkby the location of which is close to Liverpool) It pertains specifically to a headbutt administered to any unfortunate person who might happen to cause offence, or raise the ire, deliberately or otherwise of another. It is usually quick, bloody, painful, eye-watering and usually results in a complete capitulation by the unfortunate recipient.
"'e was gerrin on me effin nerves, keepin' askin fer 'is money back; so I giv im a Kirkby kiss. Sorted!"
A slang use for a punch used mostly by chavs
"If I ever see him again I'm gonna give him a kirby kiss"