Second thought: "The person who would buy all 3 of these calendars is probably... very interesting."
Third, panicked, thought: "... oh, shit, they think that I'm that interesting! Gah!"
Want to know what calendars I bought last year? Scenic Pacific Northwest, space photos, Obama quotes, Word-of-the-Day, and one with editorial cartoons. So clearly I like outhouses. And burlesque. And skiing. All at once. In fact, if they have calendars of burlesque dancers using outhouses in the snow whilst wearing ski goggles, I'll take seven.
Lesson: Recommendation systems need data - lots of it - from both the specific customer you're serving and from a large database of other customers. If you don't have that, don't bother, because bad recommendations - especially when they're so obviously, laughably bad - are worse than none at all.