There's a young white woman on stage, draped in a gigantic Tupac t-shirt and singing bubblegum lyrics such as: "All I wanted was to be your housewife." A black man with a mohican is bodypopping into her, jerking robotically as if he were lit by a strobe light. He is wearing a tutu.

Across the stage, the woman's sister is obscured behind a gold commedia mask and a baseball cap. She uses her operatic training to sing incredible, heartbreaking trills, barely looking up while she fiddles with a French Speak & Spell toy to make it say "HLM", the French shorthand for a council housing estate. A group of their friends beatbox while standing around in the shadows, while a Care Bear video plays on a big screen behind them.

"Where's CocoRosie?" shouts one heckler. It's a fair question if you haven't got past the notion of CocoRosie being just the Casady sisters, two beautiful Americans who holed up in a Paris bathroom to overcome their differences by making sorrowful music together. The narrative that accompanies their two albums and their interviews speaks of isolation, of a refusal to enter the modern world and make normal music, so their nod towards hip-hop may be confusing for some.

As will their stunning reworking of Kevin Lyttle's Turn Me On, in which Sierra Casady turns a recent chart hit into a slow, seductive call to arms. It works unbelievably well: every man on stage is drawn to her as if she was a snake charmer, slowly pulling them in. This languorousness is where CocoRosie's boldness lies, but it can also be their failing, as many of their songs seem to rise up and find their groove, only to sink back down, defeated by the passivity of their own poetry.

· At Whelans, Dublin ( 00 353 1 478 0766), tonight, and at the All Tomorrow's Parties festival (020-7734 8932) tomorrow.