In the summer of 1970, U-M Gilbert & Sullivan Society director Roger Wertenberger formed a small ensemble specializing in Elizabethan madrigals. When charter members Tom and Pat Petiet established the Comic Opera Guild in 1973, the G&S madrigal singers migrated with them. Eventually revived by the Petiets, then galvanized by the arrival of Chris and Bill Schwartz, the group has been operating as the Stark Raving MADrigal Singers since 1994.

The SRMS hold practice “warbles” in private homes, where people of all ages are invited to sit in and sing (or simply listen) while seated on chairs arranged in a ring. Each participant is asked to choose a song from carefully indexed loose-leaf notebooks filled with sheet music. Pitch pipe in hand, director Chris Schwartz conducts and issues instructions like “stop there, go back to the beginning” and “not so loud, please.” Across the circle from her sits a hale and hearty tenor who runs a llama ranch west of Ann Arbor. Flanked by altos and sopranos, he sings each word with gusto. As the group prepares to launch an unusually fast-paced tongue-twister, he announces, “We’re gonna rip it!” Afterwards he cheerfully observes: “That one really came unhinged in the middle!”

On the evening I visited, verses from Orlando di Lasso’s “My Heart Doth Beg You’ll Not Forget” were variously sung in a Texas drawl, in “Fractured French,” and breathily, in the manner of Marilyn Monroe. Another madrigal, dutifully rendered in Italian, was then done up in barnyard style, with singers imitating ducks, geese, chickens, and peacocks. Throughout the evening, additional commentary was provided by the Petiets’ wall-mounted cuckoo clock. The overall effect was that of a tale told by Lewis Carroll or Edward Lear.

While each piece is sung at first as originally written, the MADrigals also live up to their name by reprising some of the songs as pleasantly preposterous parodies. In their hands, John Dowland’s “Fine Knacks for Ladies” translates as “Five Wacky Ladies;” Orlando Gibbons’ “The Silver Swan” becomes “The Leaden Loon;” and John Wilbye’s “Adieu, Sweet Amarillis” undergoes horrific rephrasing as “I Do Eat Armadillo.”

I was particularly moved by the old English folk song “Early One Morning,” to which Tom Petiet has tailored verses describing the ecological disaster caused by the BP oil spill of 2010. Appropriately retitled “Oily One Morning,” it’s a protest song worthy of Pete Seeger or Phil Ochs.

The Stark Raving MADrigal Singers meet every Monday this month (except July 3) and reprise their annual traipse through the Art Fair at 7 p.m. on Thursday, July 20, beginning on the steps of the U-M Hatcher Graduate Library.