Rails helper method refactor
I'd write:

def gesture(klass, item, text, desc)
  element_class = [klass.to_s, "gesture"]
  url = case klass
  when :sell
    new_reply_path(item_id: item.id)
  when :alternative
    new_reply_path(item_id: item.id, alternative: true)
  when :join
    new_item_affiliation_path(item)
  else
    fail("Unsupported klass: #{klass}")
  end

  content_tag(:li) do
    link_to(url, title: desc, data: {qtip: desc}, class: element_class) do
      content_tag(:div, nil, class: element_class) +
        content_tag(:span, text, class: 'gesture-text')
    end    
  end 
end