Auto Reply to Tweet Searches

Wasn't actually sure where this would go, but if it's wrong then Mods, please move it

Ok, so I'm looking to automate a process whereby someone will post a tweet with a hashtag, let's say #Boobs

I wan to then have a Twitter account automatically tweet that person to say something. (so basically any time anyone tweeted the word #Boobs).

I've tried IFTTT but they don't allow tweet replies, only direct messages.

Any suggestions are welcome