marotte
/maˈrɒt/noun
1A baton carried by a fool or jester as a mock emblem of office; = bauble. Now historical.
2A pet notion, a craze.
Origin
Early 17th century. From French marotte object of a ridiculous and exaggerated affection, foolish idea, jester's baton bearing a head with multicoloured belled cap, image of the Virgin Mary from Marie, the name of the Virgin Mary + -ot. With the phrase to crown with a marotte, compare French coiffer d'une marotte.