Time Cock
The Time Cock was a "time ring-thing" that Iris Wildthyme disguised as a black dildo. Iris gave the Time Cock to Jenny Winterleaf for use in emergencies.
In 2008, Jenny used the Time Cock to go to 1962 with Panda and Barbra in order to save Iris from Kristoff Alucard. (PROSE: The Dreadful Flap)
The Time Cock was used to stimulate the Doctor's prostate in the Big Tardis on Trenzalore. The Doctor attached the Time Cock to the Tardis console, and executed the expangilation process. The Doctor then sat on the console and absorbed the knowledge held within the Time Cock. Some say the Doctor is less likely to know they've sat on something because of this incident.
Behind the scenes
In the version of The Dreadful Flap reprinted in The Further Adventures of Iris Wildthyme, the Time Cock was changed to a Time Neck Massager.