Silly point

Silly point was a fielding position in cricket. The Fifth Doctor mentioned it to Peri and Erimem as a possible location for Tegan, who was on the ground during the final stages of the 1981 Ashes series. (PROSE: Graham Dilley Saves the World)

Behind the scenes
Though not mentioned in Dilley, silly point was very close to the batsman and therefore "silly" for its dangerous proximity.