Cleverbot
This thing keeps me laughing, I mean take a look :
User: Hi.
Cleverbot: *noms Cleverbot*.
User: Are you cleveR ?
Cleverbot: I am clever sometimes.
User: Orly ?
Cleverbot: I'm kidding you.
User: I knew.
Cleverbot: Are you happy?
User: Yes.
Cleverbot: Why are you happy?
User: Cause I drank milk.
Cleverbot: Sound's fun. I'm glad your happy.
User: Sup ?
Cleverbot: You are not very clever, cleverbot.
User: I KNEW.
Cleverbot: Do you like Alan?
User: FUCK HIM.
Cleverbot: I won't.
User: Why ?
Cleverbot: I'm not hungry.
Try it out :
HERE