Parking in Boston is at a premium. During a snowstorm, you will often see an empty space with a chair or some other object sitting there. This is our way of saving a space that we spent hours in the cold shoveling. To park here is about the most dangerous thing your car can do, and there is a 100% chance your car will not be the same as when you left it there.
If you're looking for a parking space in the wintertime, especially if it has recently snowed, be careful. Residents who shovel the snow out of a parking spot on the street will, for the rest of the winter (and sometimes into spring), view that parking spot as belonging exclusively to them. When their car is not in that spot, they will "reserve" the space by leaving a chair or a trash can or anything else they have on hand in it. If you should remove this debris and park your car there, you may find scratches, broken windows, or some other damage to your car when you return. Be careful!!!
Don't think too badly of the Bostonian for this lapse in friendliness. There is so little parking around town - and the snow makes it that much harder to get a decent spot. I've spent hours shoveling snow & chipping ice out of a spot. And when somebody else "steals" your spot, it forces you to "steal" your neighbor's spot. Winter's nasty enough without this inconvenience!