The question before the house is jokes. What's funny? What isn't? And when does a joke move from the secure ground of being funny onto the shaky turf of being offensive?

Unfortunately, the answer to the last question is: often. In recent weeks, there have been two particularly troublesome examples of jokes told in public that lost their way.

I've received more than a dozen complaints about each of them. I'm going to retell them here not because I think they're funny (I don't), but because I'd like to alert speakers and deejays around town who may be tempted to tell such jokes that they can expect a reaction. A big reaction.

The first example concerns Sheldon Knorr, Maryland's commissioner of higher education.

Knorr was the keynote speaker at a reception held in Annapolis in October for 1,000 students from all over the state. The students were Maryland's best and brightest. They had been chosen for membership in the Distinguished Scholar Program of the Maryland State Scholarship Board. Many parents were in attendance, too.

Knorr opened his remarks with this gag:

A high school athlete was taking a test and didn't know the answer to a question. He turned to the student next to him and asked him what the answer was.

"You don't know what Old MacDonald had?" the student asked. The athlete said he didn't. The student told him the answer was "farm."

"How do you spell it?" the athlete asked.

"E-I-E-I-O," the student replied.

According to H. Kenneth Shook, executive director of the scholarship board, the joke was greeted with "a few scattered giggles, nothing more." And Knorr quickly shifted into "serious gear," praising the assembled students for their brightness and scholarly achievement.

But several parents pointed out that Knorr was sadly mistaken if he thought that a joke at an athlete's expense would sit well with top students. The reason: many of those in the audience were athletes themselves.

"What kind of a lesson are we giving our kids?" asked James Carter, a father from Severna Park who was sitting in the audience. "That all athletes are dumb? That just isn't so."

Knorr couldn't be reached for comment, but Shook said he "didn't really take the joke as a cheap shot . . . I don't think he intended to do any harm."

Perhaps not. But harm was done indirectly. Any time kids are taught by example that it's funny to mock someone, or some group, they will tend to do the same at some later time, whether they mean harm or not. We ought to be able to expect more from our educators.

And from our disc jockeys. However, on Nov. 17, WRQX-FM's morning drive-time man, Doug Limerick, stepped way out of bounds. This was the "joke" he told:

"Ever wonder what RSVP means at the bottom of an invitation to a Jewish wedding?

"It stands for 'Remember, send vedding presents.' "

Many of my callers were angered that, for the millionth time, Jews were being pictured as acquisitive and unable to speak without an accent. "Are we going to hear how long our noses are next?" asked Alfred Leibowitz of Silver Spring?

But Limerick's joke actually fails because it mocks an image of Jews that no longer bears much resemblance to reality.

All over the Washington area and all over the country, Jews have gravitated toward such fields as academics, public service and government. That's a far cry from the image of the Jewish merchant, gouging customers from behind the counter of his corner market, or the image of the Jewish retiree, thinking only of how to furnish his luxury condominium in Florida. Plenty of Jews couldn't care less whether they receive wedding presents.

And how many Jews have you met lately who pronounce it "vedding"? The simple fact is that most foreign-born American Jews are now either old or dead. American Jews may say "y'all," or "Chicawgo," or "I pahked my cah in Hahvud Yahd." But so do American Poles, American Catholics, American Indians, American Anybodies.

Alan Burns, program director of WRQX, said he "didn't see the joke as a slight and I'm sure Doug and Dude Walker (Limerick's co-host) didn't either. . . . We don't try to make our living by offending people. If we did so, it was inadvertent. Humor is tough, and sometimes you fail."

Indeed you do. But if you stop reaching up on the shelf for jokes that demean a group, you won't fail nearly so often.