They ran up the stairs, then down, then up again. Together, over and over. The neighbors wanted to complain, but how do you complain to a pair of ghosts? Worse, ghosts who don’t realize they’re ghosts?
The Super said he was trying to find new ways to tell the kids that they were dead, that they could go anywhere, do what they want to do, and not disturb the rest of the building.
But kids will be freaking kids, I suppose.