Ariana has become one of the most powerful female pop vocalists today. But this power is not just present in her vocals. This power can also be seen in her lyrics, especially now more than ever. One of the common themes in Ariana's songs is "I don't care about you". This song is also the same. Shut up is basically a way of showing how powerful and independent Ariana is, and how she won't tolerate any unnecessary criticism from anyone. She's telling her boyfriend to keep his opinion to himself, because she certainly does not need it.