Micro Servo Robot
From Tardis Wiki, the free Doctor Who reference
Micro Servo Robots (MSRs) were small robots. On Epsilon Gamma, MSRs were used for advertising campaigns. They were able to produce adverts on nearly any surface.
Jo Grant took pity on a damaged MSR and brought it on board the Doctor's TARDIS. After Jo mended its damaged leg, it plugged itself into the TARDIS and began producing adverts on the TARDIS's systems. The Third Doctor crushed the robot by stepping on it and was forced to restart the TARDIS as the adverts kept appearing. (AUDIO: Pop-Up)
