Many years ago, probably the late Sixties I went to Watford v Grimsby with a friend and his Dad, who was a Grimsby supporter. It was either a Third or Fourth Division game, but at half time a gang of kids came on the pitch and had a kick about in one of the goals. I've never seen it before or since at a league ground. A lot of the home support also changed ends at halftime, walking round to the end Watford were kicking into. I also saw that at Aldershot, I think, although I can't be sure it was there.