There's a special kind of pleasure in hating something with somebody you love. Is it healthy and positive? Eh. Who are we to say? But it sure is fun... and is one of the few occasions when hatred actually serves to draw people closer together.
This "I love you because we hate the same stuff" mug is a sweet and romantic way to celebrate you and your partner's (or friend's!) shared scorn of everything Justin Bieber has ever done.