DOCTOR: Ah! (shows her an odd device) Eureka! Do you know what that is?

LEELA: You ask me so that you can tell me.

DOCTOR: That’s right.

Doctor Who (1963-1989) British science fiction television series, original run (BBC)

14×06 “The Talons of Weng-Chiang,” Part 5 (1977-03-26) [w. Robert Holmes]
    (Source)

(Source (Video); dialogue confirmed)