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)
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.