How about "용감해져(to be brave)" for that? or 난 핑크색 옷 입으면 눈에 뵈는 게 없어. lol

I really like the second one, manyakif. It could sound a little rude, but it's no problem between close friends. 용감해지다(get brave), 강렬해지다(get strong) sound a little awkward in this case. At least I don't say these words very often, except when I say 무식하면 용감해지는 법이다(The more ignorant you are, the more daring you are). 강렬해지다 is mostly used in written Korean. 강렬한 햇빛, 강렬한 눈빛 etc.

the word '까칠하다' sounds more close to the words such as captious, fussy, carping, cavilling and picky to me or it shows abrasiveness of a person's attitude. the meaning of 'fierce' is a bit elusive to capture in korean in the sentence asked above. if you try to say you feel or become so vigorous and intense as to be seen almost as ferocious and aggressive in a positive way, then it's kind of difficult for me to come up with a korean word that takes the perfect picture of what you mean for now. but i would say in this way. "핑크색 옷을 입으면 난 강렬해져!" the word with the closest meaning to fierce in the sentence can be '강렬하다' which comes up in my mind now. but the sentence made by me doesn't have catchy and slangy feel to it. can anyone add some more appropriate words? ^^

Uh- I think of 난 핑크색 옷 입으면 까칠해져.