I've been getting reminders for all kinds of stuff, some of which I don't even know how it ended up on my calendar. Just for example a friend from work's birthday popped up and were not friends anywhere but at work??? Anyway, I looked and there seems to be no option to enable or disable holidays and special days so I'm guessing that the reminders I'm getting are from Facebook. I know it's putting all of my friends birthdays and anniversaries on there, so it's my guess that it is also providing the holidays. One thing I've noticed since the Sense 6 update is that I'm getting these reminders much earlier than I used to. Before I got them the day before now I'm getting them up to 4 days earlier. This has caused me to send some early birthday wishes, but since I'm always late it's nice to be bae at something. I can't think of any other calendars I have sync'd although I have other accounts sync'd, i.e. Yahoo, LinkedIn, AOL (maybe), FX Camera, Twitter, Tango, and Snapchat, but I think most of those only sync with my contacts.