It takes nerve to start a concert at the peak of your popularity with a song about being a has-been. But that's exactly how Barenaked Ladies opened their sold-out concert last night at Merriweather Post Pavilion: with "Box Set," a wry anthem of a fading rock star who complained that "now it seems what people want is what I used to be/ Every time I do something new all they want is 1973." With that and every other number, the five Canadian smart rockers worked themselves into a sweat to please the 19,000 fans in attendance.

As they sang under a banner proclaiming it "A Barenaked Summer's Night," vocalist Steven Page broke into dances the likes of which have not often been seen since the advent of effective anticonvulsive medication. As always, the band improvised heavily with everything from a goofy rap number about the differences between trail mix and gorp, to an ode to beans and wieners, as well as a medley of musty "progressive rock classics" by acts such as Genesis and Yes. The series of songs was performed so loosely that vocalist Ed Robertson proudly proclaimed BNL "the worst cover band in the world." The fans roared for favorites like "The Old Apartment," "Alcohol" and "One Week," BNL's near-ubiquitous rap hit, in a show heavy with kitschy props and eye-burning light displays.

Two of the bits were especially inspired. In one segment which they called "Anyone Can Be a Rock Star," they brought a guy named Jim out of the audience and had him strum the guitar around Robertson's neck in repeated five-stroke bursts. When they began playing, Jim was accompanying the band on the Kinks' "You Really Got Me," perhaps the ultimate rock crowd-pleaser. As Robertson predicted before Jim enjoyed his moment in the spotlight, "You take care of that, we do the rest, you will go home a hero." And in another routine, after a joke video in which double-bass player Jim Creeggan complained that the band is always doing the same thing, the band members emerged from behind a yellow curtain wearing white jumpsuits and hard hats and carrying identical red keyboards strapped around their necks. They then played a techno version of "Self Respect."

The signs at the gate admonished concert-goers against throwing macaroni and cheese on the stage, trying to end a concert ritual. "Macaroni and cheese hurts when you get it in the head. BNL would appreciate donations to the food bank instead." When the time came, in the song "If I Had $1,000,000," only a smattering of cheesy goo flew through the air. Robertson smiled and said, "For 19,000 people you're pretty well behaved."