If you drink, stock up now. Very shortly you may be too young to buy alcoholic beverages.

Gov. Edward J. King and his legislative bandwagon are rolling headlong after everyone under age 21 who drinks. King is determined to fulfill as soon as possible his campaign promise to raise the drinking age back to 21.

Tuesday, the governor poured statistics of rising highway carnage and school vandalism on the legislature's joint Committee on Government Regulation and blamed much of the destruction on drunken teenagers. Wednesday the committee voted on a bill to raise the drinking age. Now before the Ways and Means Committee, the bill may reach the floor of the House by next Monday and the Senate by next Wednesday.

Although amendments offered on either the House or Senate floor could considerably alter the bill, members of both legislative branches have promised not to hold it up. A special preamble ensures the bill will take effect as soon as the governor signs it.

Provisions of the bill include:

*raising the legal age for service and sales of alcoholic beverages immediately to 19, and to 21 within six months;

*raising the legal age for holding a liquor license along the same schedule as the drinking age;

*maintaining the employment age of waitresses, waiters and liquor warehouse employees at 18, but raising the age requirements of bartenders and employees of package stores to legal drinking age.

Local nightclub owners have mixed reactions to the proposed bill. "I think the bill is a bunch of baloney anyway," Patrick T. Lyons, general manager and director of public relations at the discotheque Boston-Boston, said yesterday. He added that if legislators hope the bill will get drinking teenagers off the highways, the bill will fail because it will force teenagers to drive to neighboring states where the drinking age is 18 to get liquor.

But Leo McCarthy '73, assistant manager of Varsity Liquor, disagrees. "I'd like to see the drinking age go up to 21," he said recently. "That would keep it out of the high schools. If you bring liquor into the high schools it gets down to the junior highs and even elementary school kids," he added

Both Lyons and McCarthy said their business would dip slightly if the drinking age went up to 21, but added they would make it up.

"A lot of nightclubs say they aren't worried," Lyons said, "but a lot of people are fooling themselves and are in for a rude awakening." He said many nightclub owners think they cater to crowds over age 21, but are actually drawing older men who come to look at younger women. "And when the younger women aren't there, the business will be gone," he added.

But Lyons added he would rather see the drinking age raised to 19 than left alone. "A bunch a drunken 18-year-olds are idiots," he said.