Blue stabiliser

The blue stabilisers were a component in the TARDIS which stabilised the TARDIS in flight and prevented it from rattling around. The Eleventh Doctor believed the blue stabilisers to have no purpose, other than being blue. River Song informed him of their purpose, and used them to stop TARDIS shaking, the Doctor irritatedly called them "blue boring-ers", and said the journey was no longer fun with them activated. (DW: The Time of Angels) He apparently disabled them soon afterwards, as the TARDIS no longer showed stabilising effects while in flight after this adventure. (DW: Vincent and the Doctor)