Ruby Block to Create Random Token String Without Offending

def random_token
  characters = 'BCDFGHJKLMNPQRSTVWXYZbcdfghjkmnpqrstvwxyz23456789-_'
  temp_token = ''
  srand
  TOKEN_LENGTH.times do
    pos = rand(characters.length)
    temp_token += characters[pos..pos]
  end
  temp_token
end