gistfile1.rb

class MyAwesomeClass
  attr_accessor :awesome_instance_variable
  def initialize(var)
    @awesome_instance_variable = var
  end
  def reverse!
    @awesome_instance_variable = @awesome_instance_variable.reverse
  end
end

sb = MyAwesomeClass.new("syntaxblitz")

puts sb.awesome_instance_variable #=> syntaxblitz
sb.reverse!
puts sb.awesome_instance_variable #=> ztilbxatnys