ANN ARBOR, MICH. -- "Sleep is for the weak and sickly," declares Dave Koziol's lapel button. It's an appropriate thing to wear at a conference where events are scheduled for 12:01 a.m.

The ninth annual MacHack conference, subtitled "Four Days Without Sleep," drew Koziol and about 270 other Apple Macintosh computer programmers last week. They weren't typical 9-to-5ers. They came to discuss the latest computing techniques, quaff big quantities of coffee and high-caffeine Jolt cola, and complain about and praise the Macintosh and the company that makes it.

And to hack. To these folks, that means program their brains out.

The mostly male, mostly young MacHackers have a counterculture tinge, but don't lump them in with criminals who electronically break into other computers to steal information or money, or who write data-wrecking viruses.

This crowd consists of "the best Macintosh programmers from around the world," turned loose together to "see what the synergy makes," said Doug Houseman, a Mac programmer, consultant and author in Plymouth, Mich. Houseman has been at every MacHack, and he's writing a book about MacHackers.

The Macintosh is known for its devoted following, sparked largely by its ease of use. MacHackers claim a share of the credit. Their individual and collective efforts have produced some key pieces of the software that makes Macintosh so user-friendly.

Like other conferences, MacHack has seminars and panels on such topics as "DLLs & Shared Libraries," "Extensions to Apps" and other matters that fascinate programmers and confound average folks. Participants pay anywhere from nothing to $500 to attend, depending on whether they're speaking or volunteering.

But for many MacHackers, the chief attraction is the Machine Room: several dozen Macintosh computers, printers, scanners, software-development tools and other useful digital gear, all on a network that makes collaboration easy. Sponsors including Apple Computer Inc., Microsoft Corp. and the University of Michigan supply the gear.

Open 24 hours a day, the Machine Room is the scene of feverish activity.

"It's really a fun place to be," said Eric Shapiro, a Ann Arbor-based programmer and multi-year MacHack alumnus. "You're sitting there, trying to figure out how to do something. You yell out and someone knows the answer."

The Machine Room frenzy spawns the contest for the conference's Best Hacks -- little software programs that are glitzy, fun, technically challenging and, for the most part, useless. Prizes are awarded for the best hack written in the last year, for the best hack written solo during the MacHack, the best hack written by a team at the conference and so on.

Winning hacks tend to make people laugh or drop their jaws. One legendary hack in 1992 used a TV remote-control unit to run the computer.

Shapiro wowed the crowd in 1991 when he came up with a way to replace the computer's regular beep with video clips from "Star Trek" and popular movies. VideoBeep is sold commercially by California-based Sound Source Unlimited.

But Shapiro thinks his 1989 hack, a non-winner that fiddled with the Mac trash can, was a better piece of programming. On Macintoshes, people delete files and folders by using the mouse or other pointing device to drag the file on top of a trash can icon.

With Shapiro's hack, "when you emptied the trash, Oscar the Grouch would pop out and sing at you and go back into the trash," he said. Oscar the Grouch, of course, is the "Sesame Street" character who lives in a garbage can and loves trash.

But Shapiro couldn't market his hack because the people who license "Sesame Street" characters wouldn't give him permission to use Oscar. In fact, they told him to cease and desist, he said.

In 1990 Dean Yu, a University of Michigan graduate who was working for Apple, created another classic hack that annoyed another big company. Yu's clone of the Energizer Bunny banged its drum around the network of computers, jumping from screen to screen as it traversed the network. Other programmers could hear the drum on their computers' speakers just before it reached their screens, and they would hear it fade away after the image had disappeared.

Apple wanted to put the "Net Bunny" into its operating system. But the Energizer folks turned Yu down.

Like many other MacHackers who have joined Apple over the years, Yu had to change sides at another conference highlight -- Bash Apple, at which Apple employees hear the gripes of programmers who work elsewhere.

A single company representative took the heat the first time; now the company sends a bushel of bashees, more than 30 this year.

"We keep in touch throughout the year, but this is a way to get together and strengthen relationships," said Jordan Mattson, Apple's original bashee and now a product marketing manager.

Koziol, the Ann Arbor-based programmer, agreed. "It's a good way to get feedback to Apple, and they do listen. Occasionally, they react as quickly as we'd like them to."