booby

The OED offers: 1. 'A dull, heavy, stupid fellow: a lubber' (J[ohnson]); a clown, a nincompoop. b. The last boy in a school class, the dunce. 2. A name for different species of Gannet.

The primary meaning has a first citation of 1599-1603 and the secondary of 1634. Close. Ultimate etymology is unknown. Cf. German Bube in the sense of 'fool, lubber'. Kluge connects Bube with English boy and Dutch boef 'crook, rogue, cheat'.

As for clown, the OED has: 1. A countryman, rustic, or peasant. 2. A man without refinement or culture; an ignorant, rude, uncouth, ill-bred man. 3. A fool or jester, as a stage-character (? orig. representing a rustic buffoon), or (in Shakespeare) a retainer of a court or a great house. The etymology connects it with the word clod and various words in Low German languages.

Ceci n'est pas un seing.