Just for the sake of argument, let's say your pockets are fairly bulging with fifty extra smackers. This happens to be fifty in loose change, so naturally you're sagging a bit at the seams.

Now you could lighten your load, easy, on a night for two at the Kennedy Center, and have done with it. Or you could stow it in a savings account, which sounds dull, and probably is, Or you could spend it, patiently, from now 'til next leap year, and keep yourself in movies, plays, concerts and other delights for the duration.

All you have to do is go to college.

Not as a student, you understand, unless you wallow in nostalgia whenever you see a textbook. Because you needn't enroll and live in a dorm to experience campus culture. The campuses about town are perpetually bearing the fruits of free and cheap amusements, ripe for the picking. So why not harvest away?

One recent week you could have caught, on successive nights, a mime act from Philadelphia at Catholic University; a one-man show, "Wild Oscar Wilde," at George Washington; a full-scale production of the rock musical "Hair," at Georgetown; the cult horror flick "It's Alive," at American University, and a performance by actors from the Royal Shakespeare Company at the University of Maryland.

The cost of all this entertainment amounted to seven dollars and change, which probably would buy you a bemused smile at the nearest Ticketron outlet.

This is not to say that college fare is every bit as finished as the full-price stuff; usually it isn't. But what a student production, like "Hair" at Georgetown, might lack in polish, it can more than make up for in youthful exuberance.

Even "It's Alive," a third-rate flick about a baby's binge of death and destruction, can be well worth the trip if viewed in the company of hundreds of undergraduates celebrating the end of mid-terms. In an auditorium at American University the other night, we all slouched in our chairs, the kind with retractible desk tops, made hand-shadows in the projector's beam and vied with one another to get off the smartest remark. Hardly anyone watched the movie, but it was fun.

And if you believe William Stott, vice president for student affairs at Georgetown, sharing a flick with a bunch of college kids can also be serious business.

"We're charged with the education of the young," Stott says, "and any kind of interaction that they have with the community in which they live can't help but be a plus." t

This month and next, the campuses will confront the culture maven with a dizzying array of alternatives. Here, for instance, are two dozen and five different things you can do at area colleges just between now and Monday; a lot of them are free, and only one costs more than $5.

If DANCE is your fancy, George Washington will present a student/faculty dance concert (8 this Friday and Saturday nights in the Marvin Center Theater, free), and the University of Maryland's dance department will feature the choreography of faculty member Meriam Rosen (8 this Friday and Saturday, 2 Sunday in Building EE, $4.50; call 454-4056 for reservations). Monday at 8, you can make the weekend last at College Park, where Japanese choreographer Kei Takei's Moving Earth Ensemble will perform in the Student Union Grand Ballroom ($4, tickets available at the Student Union ticket office).

The MUSIC-minded, meanwhile, can attend pianist Charles Phelps' masters recital at 8:15 Friday night in the University of Maryland's Tawes Recital Hall (free), and at 8:30 Saturday they can catch harpsichordist Elaine Camparone, fresh from rave reviews in New York, playing Bach and Haydn at the Tawes Theater ($5.50, call 454-3322 for reservations). At 8 Friday night in Georgetown's Gaston Hall, the Japanese bamboo flute ensemble Shakuhachi will offer a concert of Oriental music ($5). Gil Scott-Heron will do rythym and blues at 7:30 and 11 Saturday in American University's Clendennen Auditorium ($8.50, call 659-2601), and a group called "Jazz With Air Apparent" will do some riffs, Saturday at 8, as part of the free coffee house series at the American University Tavern in Mary Graydon Center. Soprano Eleanor Mason, of Northern Virginia Community Community College's music faculty, will sing Sunday at 3 on the Annandale Campus. Roomn 203 (free). Georgetown's Gaston Hall will echo with bagpipes, in a program of Scottish music at 8 ($5). "Herperus," a baroque chamber ensemble, will launch a Sunday afternoon concert series at 3 in Mount Vernon College's Hand Chapel ($6.50). And at 8:30 Monday night, violinist George Steiner and pianist Robert Parris of the George Washington music faculty will offer a free program of Beethoven duets at the Marvin Center Theater.

If PLAYS are your thing, American University's department of performing arts will stage "Kennedy's Children" at 8 Friday and Saturday nights in the New Lecture Hall Auditorium ($3, call 686-2317 for reservations). Georgetown's Mask and Bauble Society offers "A Man For All Seasons" at 8 Friday and Saturday in Poulton Hall ($3, call 625-4893 for reservations), while Georgetown's Arts Hall Theater stages "A Late Show," also at 8 ($2). And Howard University's drama department is presenting the musical "Babes in Toyland," through November 23 at the Ira Aldridge Theater (most performances at 8; $5 for adults, $3 for children, group rates available; call 636-7050).

ARTful exhibitionists can browse through an exhibition of student art Saturday and Sunday at The Sign of the Times Cultural Workshop and Gallery, floors 1, 3, 4 and 5 of George Washington's Gelman Library. The second floor of the Gelman, open noon to 5 on Saturday, presents a collection on "Exploration of the American West." If you're not doing anything for lunch this Friday, you might want to catch "Themes and Images in Pre-Columbian Art" at George Washington's Dimock Gallery or "Birds, Beasts and Bones," the work of art professor Meredith Rode, at the University of the District of Columbia's Gallery 900, 916 G Street NW. But better hurry: it's the last day for both shows. And at Howard University's gallery in the college of fine arts, you can scrutinize the 10th annual art faculty exhibition.There's much to see here, sculpture wrought of bicycle parts and such, and if you like it, you can buy it.

There are also a few OFFBEAT campus happenings that might edify as well as entertain. If your lunching late, why not brown-bag it at 2 this Friday in Catholic University's Boys Town Center auditorium, where Georgetown philosophy professor Wilfred Desan will lecture on the heady topic, "Belonging or Being Alone"? It's part of the Smith Counahan Memorial Lecture Series on morality and human nature, a regular feature of CU's School of Philosophy (call 635-5259 for information). At George Mason University in Fairfax, 1:30 Friday in Room 120 at the North Campus, professor Patricia Gray will talk about "The Emergence of the Virtuoso in the 19th Century," an event in the Piano Lecture Series. At 7:30 Friday and Saturday, and 3 o'clock Sunday, the University of the District of Columbia Arts Ensemble will present "Images," a reading of original poetry in UDC's Environmental Theater, 916 G Street, NW.And at George Mason's Robinson Hall, you can hear champion chatters in The Great Eastern Forensic Tournament, 4 to 7:30 this Friday and 9 to 4 Saturday.

If you're a fool for FILM, you can treat yourself to "The Seduction of Joe Tynan" at George Washington (8:30 and 11 Friday night in the Marvin Center Ballroom, $2), "Kramer vs. Kramer" at both American University (8 and 10 in the Ward Circle Building, $1) and Georgetown (8 Friday and Saturday in the Reiss Science Building, $2.50), an Australian movie, "The Last Wave," at Northern Virginia Community College's Loudon Campus (7:30 Friday, free), or Arthur Penn's "Mickey one" at the University of Maryland in College Park (8 Friday and Saturday in the Zoo Psych auditorium, free).