Gobemouche
A highly gullible person.
Person 1: You have permanent ink on your forehead....
Person 2: What?! How do I get this off?!
Person 1: Chill! It was a joke! You're such a gobemouche!
Person 2: What?! How do I get this off?!
Person 1: Chill! It was a joke! You're such a gobemouche!