Lipstick

Lipstick was an item used on Earth by (predominantly) females as a cosmetic item applied to the lips. (DW: The Visitation) It was also used to write messages with in lieu of other writing materials. (DW: The Girl Who Waited) Some lipstick, such as that owned by River Song was impregnated with poison or hallucinogenic substances. (DW: Let's Kill Hitler, The Time of Angels)