What time did you install the plugin? The plugin pulls all of the chalkboard gags from a remote repository (a pastebin.com page). Pastebin was being attacked by hackers yesterday and they were down for quite a bit.
It's possible that you picked up some weird content during that time that didn't match what the plugin was expecting.
I've just pushed a new version (
1.2.1) that will prevent the error you're seeing now in the future.
For you, would you mind deactivating the plugin and then reactivating it? On deactivation, the plugin purges its local records so it will force it to get a new version of everything which, I'm hoping will fix your issue. If not, there are some other things we can try.
All the best!