An article on the University of Toronto website points towards young women being trendsetters in language change. According to Professor Sali Tagliamonte "women lead the change" when it comes to new slang terms and that girls' language changes as they grow older to include more terms such as "like", "so" and "just".
But is this true? And if it is true, is it down to the fact that these expressions gain some sort of cultural currency that doesn't apply to male slang (often so coarse and vulgar as to never make it into respectable print, apparently)?
Perhaps it goes deeper and it's down to the fact that these terms are actually useful, often serving as adverbials, intensifying or diminishing effects of verbs or adjectives, or allowing speakers to relate more accurately how someone else has spoken. But, like, whatever...