Popcorn was a type of food.
The human forms of the Gods of Ragnarok ate popcorn at the Psychic Circus. (TV: The Greatest Show in the Galaxy)
Pete ate popcorn while watching Frankenstein on television. (TV: Doctor Who)
The Third Doctor bought a bag of popcorn while at the cinema. (PROSE: A Visit to the Cinema)
Flip Jackson used the food machine in the Doctor's TARDIS to make popcorn. (AUDIO: The Fourth Wall)
Behind the scenes Edit
In the fourth-wall-breaking cinema intro for The Day of the Doctor, Strax says he likes popcorn because when he eats them he can hear their tiny screams. As a Sontaran he enjoys this.