Manspeak amulet

The Man speak amulet was an item used in an older version of the Evil Bob random event. Originally, the player was transported to an island on ScapeRune and had to take the amulet from a chest in order to speak to the servants. This confused some Free to Play users who weren't aware of the presence of cats or Catspeak Amulets in RuneScape and so Jagex altered the random event so that Evil Bob was the one wearing it thus removing the item from the game.

The Amulet of Humanspeak is referenced in the Recipe for Disaster quest. When Awowogei is unable to converse with the other feast attendees, Lumbridge Sage comments that he must have 'lost his amulet of humanspeak'.

Also, in the Ghostly robes (miniquest), if you talk to the ghost at the wrong location, you will sometimes say "Wooo woooooo woooooooooo wooo," which are the words that a ghost will say if you do not wear a Ghostspeak amulet. When the ghost does not understand you, your character will comment that the ghost isn't wearing an Amulet of Humanspeak.

Trivia

 * According to the 9th Postbag from the Hedge, the ghostly Protester in Port Phasmatys, Gravingas, had a poorly enchanted Humanspeak Amulet which allowed him to be understood when speaking outside of the chat interface. Apparently he no longer uses it, as he can no longer be understood at all without a ghostspeak amulet.