 In early performances of the show , Stefani 's next song was " Hollaback Girl " , the album 's third and best @-@ selling single , performed in a drumming costume and singing with the audience . This was followed by an encore of " Serious " and " <unk> Pop Electric " , for which Stefani was brought out in a stretcher by the Harajuku Girls . However , in later performances , " Hollaback Girl " was saved for the encore and preceded by the two other songs . 
