Often it's a guilty pleasure because appropriating someone else's space seems at least faintly illicit. It involves asserting urban squatter's rights - a legal fiction and an ethical question mark. But what might be seen as a renegade land grab, from another perspective can be viewed as an act of enlightened environmentalism: getting maximum use out of a finite resource.

Not that such a lofty motive is what brought my friends and me to the Minnesota State Fairgrounds some 40 years ago. We just wanted to play baseball, and because we lived near the Fairgrounds, we decided to check out its possibilities as a ballpark.

We discovered that while much of the Fairgrounds was asphalt or concrete, there was one expanse of uninterrupted grass at the northeast corner. Called the Green Parking Lot, this area was used during the Fair by people with tents and trailers and was the first to fill up every August. Until then, though, the Green Parking Lot became our turf. We laid out a baseball field within its confines and held almost daily games there throughout the first two months of the summer.

What we called "the Green" was heir to a noble village tradition: the commons, a plot of land owned by no one in particular and everyone together. Of course, our green was owned by someone, and we worried at first that we'd be seen as trespassers with our balls and bats and gloves. But the cop who regularly patrolled the Fairgrounds left us alone, as did the maintenance workers whose trucks we often saw. In fact, after we had been playing at the Green for several seasons, Fair officials erected a backstop for us, thus conferring an official stamp of approval on our land grab.

Our backstop has long since been torn down, and permanent hook-ups have been installed for trailers, making the area unfit for baseball. But there will always be other fields. As another generation of urban pioneers scours the city, looking for an unused spot, Yankee ingenuity will rise to the occasion.