4. 'Teenage Dream' - Katy Perry, 'Never Been Kissed'
Look around any of the fan sites or engage in any Glee-based shipping wars and you'll soon discover that Kurt and Blaine (Darren Criss) are easily the show's biggest pairing (outside of main couple Finn and Rachel anyway) and with the most rabid, devoted following - and I happen to think it's partially down to Blaine's wonderful entrance into the Glee universe. A bullied Kurt seeks solace as well as information on the Dalton Academy and their singers, the Warblers, finding them in the middle of a rendition of 'Teenage Dream'. Criss and his fellow Warblers sound like the best boyband-slash-choir in the world here, the tempo knocked up and giving the song a blast of effervescence perhaps not found in the original. Criss is a knockout here, his vocals a blast of fun and it's such a giddy ride that sounds exactly like how a top-notch glee choir would sound like covering a good tune - not overproduced, not half-assed, just right.