Using Python and Tweepy to create a script which one mentions the account and has #Hello world in the tweet it will @ them back with a message as well within 15 seconds. You'll need to add your own consumer_key, consumer_secret, access_key, and access_secret for authorization with Twitter and applying for a developer account. The empty quotes have been noted with comments as to where the authorization keys should go. No liking feature yet or retweeting, just a simple replying twitter bot script.