"Engineers and scientists have more equipmentto play with," says Northwestern professor StanleyEigen. "A bunch of lawyers have their books. Ifthey want to come up with a great prank, theydon't have the stuff."

Eigen tells the story of a typical pre-medprank: "Years ago, premed students used to givesomething to some guy to change the color of hisurine," he says. "It's coming out blue and the guyis in a panic. Why do that? Because they have thestuff."

Dennis J. Frailey, adjunct professor ofcomputer science and engineering at SouthernMethodist University, says he used computers toengage in all sorts of mischief during hisundergraduate years.

"I put a program on a computer that caused theoperator's console to type out (once a day at arandom time) 'Excuse me, I must go to the restroom,'" he says.

"It would appear to go dead for five minutesand then it would return with the line 'Ahh, whata relief,'" says, Frailey, who is also seniorsoftware technologist at Texas Instruments.

Scientists at Harvard generally don't plan suchtechnically advanced pranks, and instead engage ina more sophisticated form of humor.

In 1987, Professor of Astronomy Robert P.Kirshner '70 was attending a conference in Italywhen he received an urgent telegram telling him toreturn home immediately.

"It said there was a supernova happening in[galaxy] M-51," says Kirshner, "and I was runningto the travel agent trying to get a flight home."

What Kirshner didn't realize, however, was thathe had fallen prey to his colleagues' practicaljoke.

There was no supernova at all, just a bunch ofchuckling scientists.

This year, on April 1, Kirshner received astrangely familiar telegram. This one, like thelast, informed him to a supernova occurring in theM-51 galaxy. But Kirshner didn't buy it.

"I was slow to believe it, especially since itwas April Fools' Day," he recalls, laughing.

But this supernova turned out to be real, muchto this chagrin.

Besides joking with their colleagues,scientists often use humor in the classroom tospark students interest, especially in largerclasses.

"Scientists not only do science but also teachscience," says Yale's Jonathan Marks. "Effectivepedagogy involves communication--you've got tomake students pay attention."