Board Thread:News and Announcements/@comment-5588749-20150308193949/@comment-24787982-20150310114705

It's a reference to Macbeth (Act 4, Scene 1) when the Wierd Sisters get another visit from the titular character.

"By the pricking of my thumbs,

Something wicked this way comes.

Open, locks,

Whoever knocks."

This has been parodied plenty before I did.