Imo, any innovation in fashion was rebellious because it stepped ahead of its age.... whether it was shortening of the women skirts, suits for women, cross-dressing, revealing outfits, new styles like hippie or punk....
if u wanna write about rebelious fashion nowadays... which might be quite hard imo since 2000s is only recycling 20th century so far... focus on the innovations in fashion last years... the ones that were talked about but didnt become part of everyday life and the ones that did.... sum could even consider simple crocs or uggs to be superugly and therefore simply rebellious... u dont have to exactly look like a clown to be rebellious if u know what i mean
id like to help you but looks like ur not pretty sure what u wanna do, so let me know when u get to something more specific...
And i think what u should focus on is prolly cross-dressing.... the androgynous menswear.. within last 5 years the male fashion transformed SO much.... from hunk models in sexy outfits to skinny teenage boys in womenswear... im just tired of going through male magazines and thinking that my mum would look good in that clothes....