Baltimore state Sen. Julian L. Lapides is a man who believes that legislating ought to be fun. An outspoken liberal Democrat from the affluent neighborhood of Bolton Hill, Lapides often refers to the General Assembly's 90-day sessions as a politician's version of summer camp.

"This is my therapy," Lapides often proclaims to anyone within earshot, which, given his usual tone of voice, includes most of Annapolis.

To mark his 20th year in the Senate, Lapides is mapping out a winter's worth of entertainment at his camp on the Severn next year, an agenda that may not endear the cochairman of the legislature's ethics committee to some of his fellow campers.

What Lapides intends to do -- during an election year -- is rein in some of the free-spending habits of Annapolis lobbyists, who collectively earned about $6 million in 1985 trying to persuade the assembly's 188 lawmakers to see things their way.

"The coziness between lobbyists and legislators has become appalling," said Lapides. "It is reaching a very serious stage."

Particularly offensive to Lapides are the enormous sums spent on meals and drinks for legislators -- about $180,000 for the three-month period according to the state ethics commission.

The senator says he was shocked when a prominent Annapolis lobbyist, Bruce C. Bereano, admitted on a radio program that he sometimes picked up restaurant tabs for lawmakers and staffers even when he did not personally attend the dinners.

"The whole purpose is to go over legislation at lunch or dinner," said Lapides. "There's no conceivable reason to pick up the tab while you're not there -- it looks like you're buying a vote. It's totally unethical."

So among the eight or nine bills Lapides plans to introduce next January will be one requiring lobbyists to be present when they buy food or drink for legislators.

Another will toughen reporting requirements by closing a loophole that allows expenditures of under $15 by lobbyists to go unreported. Lapides believes lobbyists often hide substantial entertainment expenses by apportioning them in amounts under $15 among several different clients.

Lapides also wants to prohibit fund raising by legislators during the assembly sessions, when special interests are often asked to contribute campaign funds at the very time their bills are being considered.

"It's virtually a shakedown," said Lapides. "It makes a mockery of the election laws."

Judging by the number of fund raisers held during the 1985 legislative session, Lapides may encounter some serious opposition to that proposal. But he believes that an election year is a propitious time to curb the spending practices of lobbyists because lawmakers will be under more pressure from home.

And he intends to ask for the legislative leadership's support for the bills. After all, he argues, Senate President Melvin A. Steinberg called in a number of lobbyists last year to tell them he would not allow the practice of picking up tabs when they were not actually dining with legislators.

But even in an election year, Lapides may be fighting an uphill battle. In the first place, Lapides does not belong to the go-along-to-get-along school of legislating, and many of his colleagues view him as a maverick and an irritant.

More importantly, Lapides is going against a well-entrenched tradition. For many legislators who cannot match Lapides' personal wealth, living off the fat of the land during the session is a small benefit that helps offset the $21,000-a-year salary. How are you going to keep them down at the Burger King once they've seen the Lafayette?