The greatest and worst method evARR!!!

class String
    def random_caps
        letters = self.split("")
        letters.length.times do |n|
            letters[n] = letters[n].upcase if rand(4) == 0
        end
        letters.join("")
    end
end

created after total boredom.

discuss uses, etc.

randomCaps = mapM $ \ ch -> Random.randomRIO (0 :: Int, 1) >>= \ n -> return $ [Char.toUpper, Char.toLower] !! n $ ch