I checked on what the word radical means to some young folks in the USA:

Radical:two definitions from the Urban Dictionary:

1) A radical is a person subscribing to a political ideology supporting massive, unmeasured, and rapid change. Radicalism is contrasted with conservatism that advocate minimum change, reactionary action advocating counter-change, as well as progressivismA radical would want to chang, for example, a feudal system into a completely capitalist system, or a completely capitalist system into a communist one. Another exaple of radicalism would be a person who wanted to change an Islamic Theocracy into an Atheist state.

2)A word used by people over the age of 30 in an attempt to sound cool, usually resulting in the opposite.
Useage:
Jim: (to friend) Hey check it out I got a new snowboard. 

Jim's mom: (overhearing conversation) Yeah its totally radical. 

Jim: OK you can go away now.