Joinking is a verb that describes the act of doing just a little bit more than making out with someone (the "little bit more" is undefined but is recognizable as being definitley not just making out)
To Jonk. Posing for a photograph while presenting an intoxicated, unconscious person with great enthusiasm and fanfare. Good form and proper etiquette dictate that while the intoxicated party need not be known to the Jonker, the Jonkee should not be homeless or injured.
Not unlike planking, the practice is meant as a good-natured meme.