There was a case a while back, a 16-year-old named Mark Drewes in Boca Raton was shot and killed by a homeowner as a result of this kind of prank gone wrong. The homeowner got a $750,000 judgement awarded against him, and he had to file for bankruptcy. A massive tragedy all around.
The homeowner, in a situation like this, doesn't know that the people skulking around his property late at night are playing a joke. The activity is not readily distinguishable from an imminent attack or burglary in progress. It's important that juveniles be taught that trespassing can have lethal consequences and that they risk being shot if they try to pull stunts like this.
That said, I had a recent situation where I thought someone was outside my home early in the morning and I had to get my weapon and flashlight and respond. Turned out to be nothing, but the drill gave me a very good run-through of my setup and revealed some problems that I have to address. So some good can come from false alarms and they can (and should) be treated as tests and learning opportunities.