2003. We had a chat, my creation, Starchat.ru, where people constantly hung out and communicated with each other. It had a Java applet! Nobody even remembers what that is nowadays, probably. Initially, some programmer I found on the internet wrote this thing, who then disappeared, and I took over the support.
Just for laughs, I made a bot that you could chat with by simply sending it a private message. It was always online, and not everyone realized that it was a bot. When the robot received a message, it searched through massive chat logs for messages that contained the most words from the query and had some response. A response is the next message directed at the user by someone (like “Vasya: oh just go you know where!” is a response to Vasya’s message). In the chat interface, you had to click on a message and then reply to it. In the presence of several options (and there were always several options, given the traffic of chatters), a random one was chosen.
It turned out to be a robot that very amusingly answers questions. If you ask it what its name is, it always replies with different names but appropriately, with emojis and suffixes, often swearing. Also, the bot always gave adequate responses to standard questions like “where do you live” or “how old are you.” Since there was a huge history, and they talked about everything in general, it was hard to find a question to which the system did not give an interesting/correct/funny answer.
So, the bot had an interesting side effect. If you start swearing at it offensively, it begins to swear back even more offensively. And generally, it often reacts inadequately to attacks and reproaches. Simply because in real conversations, a polite question is answered politely, and a rude one — of course, rudely. The audience had a lot of fun with this bot.
It was especially interesting to read the bot’s logs afterward. People there didn’t understand that it was a robot. They asked it questions, quarreled and made up with it. It was fun)

