Water pistol

A water pistol was an Earth-made toy. They were often designed in the shape of human firearms, and were usually made of plastic. Each water pistol required water in the barrel, which was later squirted out by pulling a trigger. However, the range of which the water was squirted out was limited. (TV: The Fires of Pompeii) When filled with gin, they were known as gin pistols. (PROSE: )

History
While visiting Pompeii on 24 August 79 AD, the Tenth Doctor used a water pistol to hold the High Priestess of the Sibylline Sisterhood, who was a halfway stage between human and Pyrovile, at "gunpoint" to gather information from her. Knowing actual guns weren't invented at that period, he was able to get away with the fact that the High Priestess believed it was a dangerous weapon, until Sister Spurrina looked into his mind and called his bluff. However, squirting the toy at the High Priestess still caused it to feel pain, since water was the Pyroviles' weakness. He later used it again on an adult Pyrovile inside Vesuvius, causing a similar effect. (TV: The Fires of Pompeii)

When the War Doctor met the Tenth and Eleventh Doctors in Elizabethan England, he griped at his future incarnations for brandishing their sonic screwdrivers as if they were water pistols. (TV: The Day of the Doctor)

In the latter half of the 20th century, Iris Wildthyme, upon meeting Sooty and Sweep when they were going on holiday to the seaside, pulled out a glass "gin pistol" and aimed it at Sweep; Sweep thought the gun was real, squeaking frantically, but Iris demonstrated it was merely filled with Bombay Sapphire by squirting it into her mouth, although she called Sweep a "daft apeth" for thinking the pistol was a water pistol.

Later that day, when black clouds began raining on people by following them around, Iris retrieved the gin pistol from her handbag, and Sooty used his magic wand with the help of the children in the audience to give himself and Sweep gin pistols too; they squirted them at the clouds, causing them to drunkenly fall asleep. After Iris left, Sooty and Sweep squirted theirs at Matthew Corbett, the host of The Sooty Show. (PROSE: )

In 2008, Royal Albert Hall was briefly invaded by a Graske armed with a water pistol he had stolen from the Tenth Doctor. (TV: Music of the Spheres)

Amy Pond pointed a water pistol at the Eleventh Doctor when he visited her home at Christmas 2013, thinking he was a caroller. (TV: The Doctor, the Widow and the Wardrobe)

Undated events
The Tenth Doctor found a water pistol in his pockets while looking for his sonic screwdriver. (COMIC: The Germ War)

The Tenth Doctor used a water pistol to find the rear entrance to the Temple of Kol-Ne-Wah. (COMIC: Final Sacrifice)

Behind the scenes

 * In the 1960s, Dr. Who's Anti-Dalek Fluid Neutraliser was released; it was a simple water pistol.