Have you ever had the urge when a party becomes a little dull to slip on an old straw hat, grab a cane and go into an old soft-shoe routine?

How about a little course in grave-rubbing, bagel-making, or chutzpah? A course in "massage a Trois," taught by Marlene Elbin, can be useful and relaxing: "A great treat for those who don't have four hands to massage them." Tony Denson may persuade you that you lived before. If you have wondered if therre is a social life for you in the evening, then Marta Vogel will talk it over with you.

The Open University of Washington, celebrating its sixth anniversary tomorrow, offers these classes and more than 300 in all. More than 5,000 students are currently enrolled. The courses are short-term and vary in price -- about $5 to $40 in the present term. They are held mostly in the homes of the teachers, with some at the Open U. offices on Connecticut Avenue or other sites -- such as St. Mary's Cemetery in Alexandria, for grave-rubbing.

The university features more than 30 cooking courses: vegetarian cooking, crepes, Oriental, Mexican, Italian, seafood.

There are courses on writing and how to sell it, getting along with others and the old soft-shoe, taught by Joe Jeff, who also gives tap-dancing. o

You can even learn to walk or run better. There's bird watching. Two-step dancing. Social kissing. The meaning of love.

Sam Reed holds classes on "Going Out Alone," and that was the one I chose to take.

"There are so many things to do in Washington, it's a shame to sit home alone because there is no one to go out with," she said.

Reed tries to help rid the students of their qualms and fears about being seen alone in a restaurant, or at the theater. Her classes are about two-thirds women, one-third men.

"We try to make them feel they are friendly and active, but have them control the evening," Reed said. "If they don't like the guy who asked them to dance or the way he's dancing, they should let him know it."

The night I attended, at the Open U. offices, the class was crowded -- 15 women and 11 men. The age range appeared to be from a young woman of about 23 to a man maybe 50. Two-thirds were from states outside the area and a third from the District.

The problems were sincere, and were treated seriously. There were questions about going to a movie along, dining out alone, trying to find a tennis partner, stopping for a cocktail after work.

Problems included phoning for a single reservation and being turned down or showing up alone and being shunted to the table behind the palm tree.

Reed had each person introduce himself and give a capsule background. She then broke the class into groups to discuss their plights.

Reed asked everyone to come up with one person why he should be intimidated when doing things alone.

Some said they felt consipicuous. Some did not feel self-sufficent enough to go out alone. Others wanted to share a joyful experience with someone else.

Reed handed out a tip sheet to hel allay fears. It began, "Everyone is NOT looking at you.

"Or, if they are, what's wrong with that? Make a good impression."

Another tip, about personal safety on the streets, said that in case of trouble, yell FIRE, not HELP. People respond quicker to a cry of fire than of help, Reed said.

People in the class were told to be positive, confident, not to act ashamed or to be uncomfortable. They're told the first few times they're out may not be easy, but that they should keep at it.

They discussed coming home at 6 in the evening from their jobs and turning on the TV set and starting at it all night.

To combat this, each person was asked to propose something positive they would be comfortable doing.

A young woman determined that she would stop for a glass of wine in a hotel bar that was suggested as a place she would feel comfortable.

A man said he would enter a bar near his apartment on Capitol Hill and have a beer in a crowd.

A soft-spoken young man said, "I will go to a movie alone."

The following week, one woman related that the course confirmed for her that she was behaving quite normally by going out alone. "I am dealing with people all day and I find it a pleasure being along after a hectic day," she said.

Quite a few of the teachers at the Open University wear two hats, or more.

Marcia Mazur spends her days workings at the National Education Association as a secretary and helps with some of the speech-writing for her boss. In some of her spare time, she teaches the writng of greeting cards. Other times, Mazur holds classes on baking bagels or bread, and some nights the course becomes omelets and crepes.

"I've been teaching four or five years and have turned out over 750 bagel students," Mazur said. "My classes are small because I have a small apartment and a small kitchen. I keep them to maybe 10 or 12."

Marta Vogel, a graduate of the University of Missouri and Texas Tech who wants to become a writer, teaches "Is There Life After Work?"

Curious about why a roomful of men and women would wonder together what to do after work, I was told by Vogel, "Oh, I've seen a few sparks fly."

Some of these students are workaholics in need of slowing down to find what they want in the way of leisure, said Vogel. Some "feel that they have to find someone with an interest in what they want to do."

Marlene Elbin teaches massage. She is 36 years old, and received a certificate in 1974 from the Potomac Massage Therapy School in D.C.

Elbin began teaching in 1976 and teaches separate classes in foot, back and head massage besides "Massage a Trois."

Elbin was upset that disreputable massage parlors are hurting legal masseurs. "It's hard for them to advertise without getting obscene phone calls," she said.

"People associate touch with two things, sex or punishment."

Elbin plans on a new program this spring in a quiet place in Virginia. "We will call the course, 'Rubbing and Tubbing.'"