Computer hackers of today set their sights on credit card information and other valuable intel that can be sold on the black market or used directly. But, Kaminsky said, in the early days of the Internet, hackers were often just trying to maintain long-distance friendships.
"Until recently, a major motivator was, 'I have friends who live far away, and I want to talk to them," he said.
That motivation gave rise to a high-tech subculture of "phone phreakers" who learned how to take control of the phone network to give new meaning to the prank phone call.
In one legendary case, he said, phreakers hijacked all incoming calls to a Southern California city in the early 1970s and said it had been leveled by a nuclear explosion.
On his Web site, John Draper, aka Captain Crunch (one of the more prominent phreakers), references an attempt by Apple co-founder Steve Wozniak to reach the pope via phreaking and pretending to be Secretary of State Henry Kissinger.
"There have been pranksters for as long as there have been people," Kaminsky said. "And whatever technology is available to have a little fun is certainly going to be used."
Last year, "Rick Rolling" was the April Fool's joke of choice.
The Internet phenomenon duped users into watching one-hit-wonder Rick Astley sing "Never Gonna Give You Up."
Millions of unsuspecting Web surfers were tricked by friends who sent them links to the song under the guise of something they'd actually want to see. But instead of the latest celebrity video or political testimony, the victims got the awkward stylings of Astley.
Although the origins of the prank are murky, the hoax grew on April 1 when YouTube disguised links on its homepage to direct viewers to the video.
Even tech-savvy entrepreneurs like Westheimer got some mileage out of it.
"One thing I did last year, we created a fake tiny URL shortener. You would take that URL, and it would Rick Roll everyone," said Westheimer, who has a particularly fun time playing the April Fool's jokester, as his birthday is April 1.
The hoax came from an older Internet trend called Duck Rolling, he said, which worked just like a Rick Roll but took surfers to a picture of a duck on wheels.
The Web-based design tool Aviary also had a bit of fun last year on April 1. The image editing company launched a new tool called Dodo that promised to take a photo of someone and show you how he or she would look older and younger.
Billed as a "Web-based time machine," the company posted before and after images of people and places.
From the moment the company "launched" the service, people started writing to the site asking how they could download the application. (Although handfuls of doubters quickly recognized the trick for what it was.)
The beauty of the prank was that it involved an element of believability, Westheimer pointed out.
"I heard they still get people asking them about it," he said.
In 1965, the BBC interviewed a professor who said he had invented "smellovision," a device that would allow at-home viewers to smell the aromas that matched the events on screen.
According to MuseumofHoaxes.com, he demonstrated the technology by putting coffee beans and onions into the machine and then asked the home audience if it could smell anything.