fashion victim
US /ˈfæʃ.ən ˌvɪk.təm/
UK /ˈfæʃ.ən ˌvɪk.təm/

1.
a person who dresses in an extreme or uncomfortable way in order to be fashionable
:
•
She looked like a total fashion victim in that oversized hat and tiny shoes.
•
He's such a fashion victim; he buys every new trend even if it doesn't suit him.