bro, need to bleach...i did it before, got a blue mohawk during my punk rock days, hehe...
the bleaching hurts like hell...and bcos the colour is applied onto bleached hair, it wont stay for long as the hair is "dead", lasts about a week or 2...then gotta re-dye. $60 for bleaching, cutting of mohawk, and dye blue.
anyway, after a week or 2, when the colour runs off to a ugly and pale tone, i would go to a shop in East Point Mall called "Jean" to buy lolane blue hair dye(DIY dye), which also lasts for a week or 2, $6.50 a box. They had green colour too...but i advise u to get the bleaching n first dyeing of green at a salon, dun DIY, bleach cannot "play play"...