Yo-yo

A yo-yo was a round toy which was spun up and down on a string.

While at the Time Lord Academy, the First Doctor would skip classes to practice yo-yos and juggling. (PROSE: Match of the Day)

The Second Doctor gave Mindy Voir a yo-yo in exchange for signing his copy of one of her albums. (AUDIO: Helicon Prime)

The Third Doctor, realising that the Time Lords had programmed his TARDIS to always return to Earth, compared himself to "some kind of a galactic yo-yo". (TV: The Claws of Axos) On Silurian Earth, a yo-yo was found in the pockets of the cloak on the Third Doctor's body. (PROSE: Blood Heat)

The Doctor's fourth persona was the one who most frequently kept a yo-yo on his person. Although he once used it to test local gravity (TV: The Ark in Space), he apparently used it primarily for fun. His skill with the yo-yo appeared to increase over time. (TV: The Android Invasion, The Brain of Morbius)

Leela spun the Doctor's yo-yo, thinking that it was part of the TARDIS' magic. (TV: The Robots of Death)

Romana once used the Doctor's yo-yo to test local gravity, and performed a complex figure-eight with it. (PROSE: The Romance of Crime)

It took Ace two weeks and "tons" of peer pressure to learn to use a yo-yo. (PROSE: Love and War)