A phrase used in social situations. You may actually like McFly, but you are looked upon more kindly if you don't, even though it is as trivial as "What is your favourite colour?" it is more fasionable to be SEEN to hate McFly, even though they're actually quite good.
A: Do you like McFly?
B: No, I hate McFly
B: No! They're good.
A: In which case, I can't be seen to socialise with you
B: Well, that's just tedious.