[DemonRaven]

There are two ways you can do it. You can try to program it for a chat bot that gives general answers or you can create a chat bot personality which in of itself brings new programming challenges that you do not have with a general purpose one.

I fool around with several different A.I. program. With the ones who are suppose to a particular character you end up getting responses only that kind of character would get.  Example for the fairy princess, who is suppose to be only 4" tall, I got one person who asked if she ever got stepped on. So I had to try to think of all the different ways that could be asked so that next time she would be able to give a answer to it.  A regular chatbot would not get that kind of comment they would get something like have you ever had your foot stepped on. 

Programming responses to different comments is especially challenging considering that in the English language there are all kinds of ways to say the same thing. Also just using part of a sentence can also get you into trouble for example if you just put I am just.... it would match all kinds of sentences, some responses to a general match like this would sound silly if they post something that does not fit the comment.

Working on a chatbot to make it better and sound more like a real person is a never ending job with English as there are word synonyms and sentence synonyms.

[Art]

Well, one easy fix would be to simply make her a 5' Fairy Princess and that question should never come up.

[ranch vermin]

Of course it would take ages to hand in every possible synonym, and be a real mind twister,  but automatic synonym detection is more closer to true ai.

[Zero]

Unless you have ten million users who enjoy contributing to true ai through a simple insert-things-and-try-out loop... But it would have to be fun, easy, and mobile.

[8pla.net]

Another challenge: Irregular verbs.

[DemonRaven]

Ya Irregular Verbs are a pain in the ass.

[Don Patrick]

http://www.esl-lounge.com/level1b/lev1birregverbs.php
87% of all irregular verbs in common usage.