'Booby prize' definitions:

Definition of 'booby prize'

noun

A prize given to one who finishes last in a contest

From: GCIDE

Booby \Boo"by\ (b[=oo]"b[y^]), n.; pl. Boobies (-b[i^]z). [Sp. bobo dunce, idiot; cf. L. balbus stammering, E. barbarous.] [1913 Webster]
1. A dunce; a stupid fellow. [1913 Webster]
2. (Zool.) (a) A swimming bird (Sula fiber or Sula sula) related to the common gannet, and found in the West Indies, nesting on the bare rocks. It is so called on account of its apparent stupidity -- unafraid of men, it allows itself to be caught by a simple and undisguised approach. The name is also sometimes applied to other species of gannets; as, Sula piscator, the red-footed booby; and Sula nebouxii, the blue-footed booby. (b) A species of penguin of the antarctic seas. [1913 Webster]
Booby hatch (a) (Naut.), a kind of wooden hood over a hatch, readily removable. (b), an insane asylum. [Colloq.]
Booby hut, a carriage body put upon sleigh runners. [Local, U. S.] --Bartlett.
Booby hutch, a clumsy covered carriage or seat, used in the eastern part of England. --Forby.
Booby prize, an award for the poorest performance in a competition; hence, metaphorically, the recognition of a strikingly inferior or incompetent performance.
Booby trap (a), a schoolboy's practical joke, as a shower bath when a door is opened. (b), any concealed device causing surprise or injury when a usually harmless object is touched; -- in military operations, typically containing an explosive charge. [1913 Webster +PJC]