I have a couple that I used to love doing as a kid, neither of which was looked on favourably by certain parties 
Sledging down the old coal slag heaps was a favourite that the old NCB didn't like (on the rare occasions when they actually spotted us doing it)
The other main one was a summer activity ... picking wild fruit (of which there was plenty), and for a couple of weeks each year, following the trucks from the local farms (Rhubarb Triangle) and picking up the fruit that dropped out of the back ... learned how to make crumbles and pies the first year I did that 
Briefing against women ministers in Westminster



