The Diogenes Club was a gentlemen's club situated in London.
The Third Doctor frequented the Diogenes Club, but was thrown out after one time when his seventh incarnation showed him the answer to the crossword he was doing. The Doctor's earlier incarnation shouted at his older self, breaking the rules of silence. (NA: All-Consuming Fire)
Behind the scenes
This fictional club first appeared in the Sherlock Holmes stories.