syl

We did something similar for our site http://jokels.com. We'd search Twitter every 5 minutes for the phrase "Tell me a joke" and reply to people with a random joke from our site. It was (usually) very well received by the random people we tweeted at. We found out pretty quickly that when people say "tell me a joke," they're feeling blue. It looked like we cheered a lot of people up.

Twitter banned us after a few days.

We tried our best to make the tweets not spammy (i.e. no links, the jokes fit, only show 'clean' jokes), but it wasn't good enough. Twitter never responded to us about our questions. They just reinstated our account. It was a fun few days, though.