calamus >
I actually did that once.
I was working out of town and apparently while I was gone during the day a group of children used my site to play in. Okay, no harm done but that night they came back while I was having a fire with their parents and continued.
My protests fell on deaf ears. Eventually they left. Next evening they had a fire to which I invited myself complete with cooler and my own chair, took on of the best spots near the fire and was diligent in interrupting conversations with useless bits of information whenever possible. I ignored all request to depart. I did so eventually and never saw them again near my site.