48 - Does This Drink Taste Odd (S4, Ep3)
We watch "Planet of the Ood" (Series 4, Episode 3) where the Doctor and Donna travel to the aforementioned sphere to revisit a glossed over wrong from the Doctor's past. Whilst there, the Doctor encounters another Harry Potter cast-mate, Donna denies being coupled with the Doctor yet wonders aloud why everyone thinks she looks single and Ood Sigma claims to hold the cure for baldness. If only Ood Gamma had the cure to chronic back hair. Then sign me up Ood Gamma!