Mini Doctor Who Adventures (DWA 352 comic story)
From Tardis Wiki, the free Doctor Who reference
An instalment of Mini Doctor Who Adventures was printed in DWA 352.
Summary
While out with Clara, the Doctor becomes aware that they are being followed. He turns to see a giant duck, that says "mooo!" The Doctor quickly figures out that the duck is actually a Zygon. After changing back to its true form, the Zygon asks the Doctor how he guessed. The Doctor answers; "ducks don't moo!"
