Ah, summer. The kids are out of school, which means it’s time for my young sons to take up favorite vacation pastimes like baseball, bike riding, lemonade stands and duping the world with elaborate hoaxes about UFOs on YouTube.

It was a rainy day, and our three boys were confined inside the house doing what brothers usually do — socking one in the nose and blaming the other for the trouble. I was used to this. A few minutes later, however, came total silence. If ever there was a sign that the boys were up to no good — the kind of no-good that usually results in a call to our homeowner’s insurance agent — this was it. I decided to poke around.

In the kitchen I found our 10-year-old with a cheap plastic digital camera and our 4-year-old with a circular LED light purchased from Wal-Mart for $4.88. The younger boy was reflecting the light off the kitchen window while the older boy shot a pixilated video clip. I have to admit: The reflection did look a little like a weird flying saucer, but the narration by my son sealed the deal.

“It’s an alien!” he exclaimed in his most dramatic, breathless voice. “Oh my God, look at that!” (The video can be viewed below).

It all seemed so sweet and funny — two would-be Steven Spielbergs, one in pre-school and the other in elementary school, together serving up a Close Encounter of the Fraudulent Kind. Mostly, I was grateful that they were entertaining themselves indoors, without bloodshed, on a rainy summer day.

And then they posted their video on YouTube.

Within an hour, they had their first 100 hits. And then another hundred. And another. Before long, their 18-second clip with the take-notice headline “UFO Over the Rocky Mountains!” was the subject of an intense international debate.

Some viewers pronounced the video as conclusive proof of the existence of extraterrestrials. Others denounced it as a fake, but with impressive and elaborate CGI imagery.

My little 4-year-old and 10-year-old hoaxsters were thrilled. Adults from around the world were paying attention to them! They went to bed that night with dreams of Hollywood in their heads.

When they woke up the next morning, though, they learned a hard lesson about the movie business: Overnight they had been struck by pirates.

Their fake UFO video was so convincing that it was picked up by the Paranormal Network. Shortly after, another UFO site copy-and-pasted the video, and another, and then even a foreign-language site calling itself UFO Video Italia. Somebody else somehow stretched the 18-second clip into a two-minute epic, complete with ultra-slow-motion zooms and dramatic backing vocals that seemed to come from a strange marriage of Jerry Bruckheimer and the Mormon Tabernacle Choir.

Boy, was I mad. All this work by my own two sons and now all the glory, thousands and thousands of precious Internet hits, was being hijacked by some shameless YouTube pirates. Oh, the nerve!

Surprising thing was, it didn’t bother my sons a whole lot. As my 10-year-old said: “Don’t worry so much, Dad. It’s the Internet. These things happen.”

And so here I was, the father of two baby-faced boys who fooled the world with a $99 camera and a $4.88 light from Wal-Mart. And I couldn’t help but think that summer vacations have sure changed a lot since I was a kid.

Mark Obmascik is a Denver writer and author of a new book, “Halfway to Heaven” (Free Press, 2009). He can be reached via markobmascik.com.