Steve Martin appeared on Late Show with David Letterman last night, and while he had an enjoyable story to share about having Sir Paul McCartney sing on one of his new bluegrass songs, Letterman also wanted to know what Martin gets out of using Twitter.

So Martin explained himself. If you're not following him already, he's @SteveMartinToGo. If you are following him, then you know that he's just as likely to spin a tall tale about tourism as he is to offer a quip or reply to a fan.

Roll the clip!