'Les Rock Stars' (Translation 'The Rock Stars') were a French musical group shown performing in Paris after Carl claimed that he loved everything in France except for the fact that they had "A lame-o version of rock and roll."
The song they were singing only had three lines:
Rock and Roll! Rock and Roll! Rock and Roll!
However they were later shown driving on scooters with the lead singer singing what seemed to be an improvised song, about how 'Everybody should eat fromage!'