Tick-Tock Hilda's Clock is the twelfth episode of the fifth season and the 109th overall episode of Sabrina the Teenage Witch.
On her 650th birthday, a visit from old friends who are now parents sets Hilda's very literal biological clock running at an alarming speed. Hilda takes her clock to be serviced, slowing it down, but when Sabrina loses it, Hilda decides she must have a baby as quickly as possible (in 48 hours or she will never conceive). She decides to find a random guy and get married at the court house. But when Sabrina volunteers to give up her biological clock for Hilda, she is touched by this gesture and decides not to marry and not to take Sabrina's clock. As the episode concludes, Josh finds Hilda's biological clock.