To put the edges of two old or dull butter knives on the top of a hot stove for a few minutes until extremely hot, and to then pinch small pieces of weed under a cut-out, oversized plastic gallon fruit juice container that has a thick ring of ice/snow inside.

When two people sleep with each other, but they are back to back.
Their backs are touching while they are sleeping.
The term "kniving" derived from the terms "spooning" and "forking"