The University of Maryland junior had sneaked a flask of bourbon into the fraternity ball and was sharing it with his date. And because 15 security police were roaming the ballroom of the Sheraton Washington hotel to discourage the drinking of hard liquor, the pair was being discreet.

"I know we're not supposed to have this," said the tuxedo-clad 20-year-old, raising the flask from beneath his table, "but I'm not about to pay $2 for a beer or a glass of wine. It's not worth it."

In any other year, a hip flask of bourbon might have been standard equipment for Maryland's annual Intra-Fraternity Council ball. But now, almost seven months after the state raised the legal drinking age from 18 to 21, students say they are taking extra care to stay within the law--at least in public. And some said they are holding more private parties around the College Park campus or traveling to bars in the District, where the drinking age is 18.

"People are finding new ways to do their 'serious' drinking," said Dave Ennis, a 21-year-old Maryland senior from Flemington, N.J. "We have accepted the change in the drinking age. We were prepared for it. But everybody knows there are ways to get around it."

Ennis was one of more than 2,000 Maryland students who trooped to the Sheraton last Thursday night for the IFC ball, an annual party moved to the District this year from its traditional location near Baltimore because of the new drinking age. Except for those persons already 18 when the drinking age was raised last year, Maryland law sets 21 as the legal age for purchasing any alcoholic beverages. In the District, 18-year-olds may buy beer and wine; 21 is the legal age for buying hard liquor.

Maryland's age hike has prompted college officials across the state to try to curb underage drinking. Towson State College requires its students who are old enough to drink to wear plastic wrist bands at events where alcohol is served, and while underage students are not banned from those events, Towson officials already have noticed a decline in attendance.

At Goucher College in Towson, students old enough to drink have been issued color-coded identification cards, and student aides are assigned to parties to ensure that those drinking are old enough.

And at College Park, the number of fraternity and sorority mixers is down by roughly a third, following the administration's virtual ban on beer at those events.

"We won't approve a liquor license for events aimed at underclassmen," said James M. Osteen, the school's director of campus activities. "Campus policy still allows beer, but only when it's legal."

Osteen said all of the university's 25 fraternities complied with the regulations on parties during the fall rush period and during spring rush, which ended a week ago. None of the social organizations were cited for violating the 2 a.m. closing time for weekend mixers or for serving alcohol to underage students, Osteen said.

"The student leadership has been quite responsible about this," said Osteen. "Some young people have been turned away from these events because of their age, but by and large, the law has been accepted--even if the students don't entirely agree with it."

Several campus organizations have switched to private parties--events that do not require a school-issued liquor license, according to Osteen and several Maryland students. "We own our own house, so a private party is no problem," said Ennis, a member of Theta Chi fraternity. "But some of the fraternities were getting pretty frustrated by the ban on beer. A lot of them just called private parties."

"The new law put a real crimp on fraternities," said Kimberly Hall, a 20-year-old speech communications major at Maryland. "Under the law, I can drink beer and wine, but I don't. I drink liquor, and a lot of my friends do.

"Let's face it: when you're 18, 19 or 20 years old, you're going to drink," said Hall, a junior. "All the law has done is made drinking more underground."

Tom O'Grady, 21, a Maryland senior from New Jersey, said some underage students "are simply doing their drinking at home. They can usually find an upperclassmen to get them a case (of beer) or a bottle."

But that too may change. By 1985, Maryland officials anticipate that 75 percent of the student body will be too young to drink legally. One recent study Osteen's office conducted showed that 45 percent of the current freshman class is underage.

"I expect that next year when even more students are underage, going to D.C. (bars) will be quite popular," said Osteen.

Several of the Maryland students dancing until 2 a.m. at the IFC dance said their drinking habits were unaffected by the higher drinking age. "For some of the kids here," said one female junior, "the hardest thing was changing their attitude. The law is hard to adjust to, but we have to abide by it."