TIn my elementary school there was an exercise called a civil defense drill, which was similar to a fire drill, except that students hid under their desks instead of "skip-walking" outside to wait for the school to burn.

Both drills were triggered by bells that ordinarily signaled the end of a class. If the bells continued ringing, that meant fire. If they rang in short bursts, that meant "commies" were coming.

Fire drills were fun, but anybody who thought we would simply march away from a burning building single file -- girls first -- had never seen us trample each other when the lunch bell rang.

Civil defense drills were something else. You could run from a radioactive mushroom cloud, but you could not hide. You just had to say your prayers and be ready to meet your maker.

I feel that way about our newest drill: the bomb threat. Nearly every day, some building is evacuated in Washington because someone claims that explosives are hidden here or there.

As a result, I get searched, monuments get closed, parks are cleared, storage lockers are removed from bus and train stations and hundreds of working hours are lost -- for nothing.

Are Libyan terrorists behind this? Consider, instead, people like Paul Louis Waltz, 33, of no fixed address, who was arrested by D.C. police in December on charges of making a series of bomb threats that resulted in the evacuation of thousands of employes from 20 government buildings. Waltz has been ordered to undergo psychiatric evaluation at St. Elizabeths Hospital.

In recent months, a D.C. City Council meeting was halted because of a bomb threat, the Prince George's County Court House was emptied because of a bomb threat, the USA Today building was evacuated because of a bomb threat and the Bethesda Metro station was closed because of a bomb threat.

On one day, Dec. 5, 1985, 20 bomb threats were made against federal buildings, including the departments of State, Justice, Labor, Commerce, Interior and Energy and the U.S. Capitol, the one place where a bomb once actually exploded, although a threat was not telephoned in that case.

Nearly 100 percent of the bomb threats that have been called in have been hoaxes. Yet, on any given day, the sidewalks are cluttered with government employes who have been evacuated and whose workdays have been completely disrupted.

It's becoming a joke.

"What's going on?" a man inquired as he passed a group congregated outside the American Federation of State, County and Municipal Employees building on L Street NW. "A picnic," an employe replied.

It was the second bomb threat "picnic" in a week.

Like too many fire drills, this is a sure-fire way to make people forget about the seriousness of the matter. A terrorist strike will most likely occur when you least expect it -- maybe in the midst of this rash of weirdness; then again, maybe after all is quiet.

What we are encountering now, however, are not terrorists, but terribles -- people who call in threats to the IRS so that a tax lien can be postponed, people who call in threats to their school because they didn't study for a test, people who call in threats to former employers because they were fired.

According to the D.C. police department, there have been 159 bomb threats between April 14, the day of the attack on Libya, and April 29, compared with 40 for the whole month of March. The targets have included schools, hospitals, restaurants, airlines, bus stations and news organizations. So far, police have turned up nothing -- except a few "suspicious" packages.

Depending on where you work, bomb threats are handled like old-fashioned fire drills, with everyone evacuated. In some places, it's like a civil defense drill, with everybody just waiting it out -- that is, if they are told about it at all.

The decision is up to employers and school principals.

If it were up to me, I'd go the civil defense route.

Look at it this way: If someone really wanted to blow you up, why would