Randomizing an Array

I'm trying to randomize an array, and this is what I have:

arr_set_unordered = randomizer(arr_set)

  def randomizer(arr)
   result = arr.collect { arr.slice!(rand arr.length) }
  end

It does randomize it, but it only returns 3 values instead of the 5
values that I'm expecting. Any ideas why?

Thank you!