"Stars Forever," Momus's latest album, features 30 "song portraits" of people who paid $1,000 each for the privilege of being depicted musically by the puckish Scottish songwriter. Sunday night at the Black Cat, however, the bottom dropped out of the song-portrait business when Momus offered to write a few on the spot for $10.

He did two, and frankly they weren't the show's most polished numbers. Still, the interaction with the audience made for some of the most entertaining moments of an evening that also featured Momus and his French sidekick, Toog, both of them wearing kilts, sword-fighting to the strains of the "Braveheart"-mocking "Tinnitus."

Accompanied by recorded synth tracks, Toog's keyboards and occasionally his own rudimentary guitar strumming, Momus concentrated on songs from "Stars Forever." These may not have been as personal as the older tunes he performed, which included "Space Jews" and "Maoist Intellectual," yet both varieties of song demonstrated his genius for melody and mockery.

Toog opened the show with a set of simple synth-pop songs about odd reveries and everyday frustrations. Most of them were in French, but the singer made the translation with English summaries and broad physical gestures.