This script likes and comments on posts posted by your friends. Could be useful while replying for birthday wishes :)

fb_reply.rb

require "koala"
@graph = Koala::Facebook::API.new("fb_app_token")

feed = @graph.get_connections("me", "feed")

feed.each do |f|
  @graph.put_like(f["id"]) # like wall post
  @graph.put_comment(f["id"], "Thanks a lot :)")  # comment on wall post
end