Joke

The Eleventh Doctor once included a joke and two diagrams with proof of faster-than-light travel to convince a body of geniuses they should take his advice about how to save the world from annihilation by the Atraxi. (TV: The Eleventh Hour)

A running joke between Lim and Mitch was that Lim kept her phone on all the time and was an instant replier. (TV: Resolution)