From TARDIS Index File, the free Doctor Who reference.

A yo-yo was a round toy which shot up and down on a string. The Doctor sometimes kept one on his person. He largely used it in his second and fourth personas to test local gravity. (DW: The Krotons, The Ark in Space). However, his fourth self may have gotten so used to using it scientifically, that he actually began to simply find it fun to play with. Indeed, his skill with the yo-yo appeared to increase over time. (DW: The Brain of Morbius, The Android Invasion)

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Yo-yo

From Muppet Wiki

The Yo-Yo appeared on Sesame Street in the Elmo's World episode "Up and Down." This talking yo-yo can move back, forth, and upside down.

From the RuneScape Wiki, the wiki for all things RuneScape

Yo-yo

Release date	21 December 2004 (Update)
Members only?	No
Quest item?	No
Tradeable?	No
Equipable?	No
Stacks?	No
High Alchemy	6 coins
Low Alchemy	4 coins
Destroy	Drop
Store price	Not sold
Examine	A gift from Santa.
Weight	0 kg

A player plays with a yo-yo.

Yo-yos are holiday items which were made available during the 2004 Christmas event from 21 December 2004 for about two weeks. The yo-yo can be right-clicked to perform tricks, such as "walk", "loop", and "crazy". If a player loses their yo-yo, they may go to Diango in Draynor Village and ask for another. Today yo-yos are discontinued.

During the 2004 Christmas event, Father Christmas was found in several cities including Varrock, Falador, Ardougne, Catherby, and Yanille. When players talked to him and asked for a present, he would give a yo-yo. Santa only gave one to each player.

On the first day of release, when a player died in the Wilderness, there was a chance the yo-yo would not return to Diango and it would be lost forever. As a result of time, Yo-yos are quite rare nowadays.

The yo-yo's options

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Yo-yo