OUR Beer of the Week is about as unusual as beer gets and I don't know whether to laugh or cry or just scream. The beer is Lagunitas Undercover Investigation on Shutdown or "Whatever, We're Still Here" , from Lagunitas Brewing in Petaluma.

Five-star-world class status isn't for the beer, although it's a typically delicious, major Lagunitas brew: 9.9 percent alcohol by volume, pale barley malt, a touch of wheat, Horizon bittering hops and a mix of mild and spicy Willamette hops, plus Centennial and Liberty hops that effectively mask the high alcohol.

Here's the story: Lagunitas, with its roots solidly in Petaluma in Sonoma County, a county that is home to many a marijuana stash, long held a beer tasting every Thursday evening: $2 beer, free food and music. Founder Tony Magee explains they advertised in a weekly newspaper, under the headline: "420."

The term 420 started, I understand, as the time — 4:20 p.m. — a group of students met to light up joints. Today, it signifies the weed itself. Anyway, the Lagunitas tasting always started at 4:20 p.m. "We were having fun with it," Magee says. "It wasn't like a giant pot party. There might have been three or four people out of 70 smoking pot. It's like, well, this is Sonoma County."

But the state Alcohol Beverage Control Board got the idea that Lagunitas or its employees were selling dope at the tastings. So, for eight weeks, they sent undercover investigators, a man and a woman, to the tastings to try to buy marijuana.

They had no luck. "People kept trying to give them some," Magee says. Finally, the ABC gave up and on St. Patrick's Day, 2005, they cited three people, including one Lagunitas worker, two for possession of marijuana, one for possession for sale.

ABC spokesman John Carr says he isn't sure, but Magee says charges were dropped against all three.

Bottom line: The ABC suspended Lagunitas license to sell beer for 20 days and placed the company on one year's probation, ending Nov. 18. Magee got the message. Although it began in his kitchen in the hamlet of Lagunitas in Marin County, the craft brewery's now a multimillion dollar business with 26 employees.

"Once in a while, God — the ABC — drops in and tells you he's in charge," Magee says.

"Last year, we made 32,420 barrels of beer," he says. "No kidding, that number was in our report (to the federal government)."

Proving there's still free speech: Lagunitas released Undercover Ale as a regular seasonal. Magee has a lot to say about it — in very fine print on the label — see our blog at http://www.beernewsletter.com and http://www.insidebayarea.com/beerblog for details.

An explanation of 420 can be found at: http://www.snopes.com/language/stories/420.htm

Staff writer William Brand publishes What's On Tap, a consumer craft beer and hard cider newsletter. His column runs every other week. Write him at whatsontap@sbcglobal.net or P.O. Box 3676, Walnut Creek, CA 94598, or call (510) 915-1180.