class Sampson < Character
  def when(event, &block)
    @events[event] ||= []
    @events[event] << block
  end

  def bite_thumb
    call_event :bite_thumb
  end

  private

  def events_for event
    @events[event] || []
  end

  def call_event event
    events_for(event).each(&:call)
  end
end

sampson.when(:bite_thumb) do
  gregory.ask "Do you bite your thumb at us, sir?"
end

sampson.bite_thumb # => Abraham asks, “Do you..."