We find it impossible that Clara has not learned that saying "that's not possible" is a waste of breath.
The BBC has us pegged. We'll pretty much latch onto any news about The Day of the Doctor, and this taunting 13 second clip leaves us with a ton of questions. Will we finally find out what's up with the Doctor and Queen Elizabeth? How is Clara still shocked by things? Who is that wearing Tom Baker's scarf? WHY ONLY 13 SECONDS?