Green’s Dictionary of Slang

1. (US campus) a greedy, materialistic young woman.

1938

N.Y. Herald Trib. 14 Oct. 24/2: College students appropriated the word ‘jeep’ as a synonym for girls who demanded expensive good times. (Eugene the Jeep ate nothing but orchids).

2. (US) a stupid, inept or inexperienced person.

1938		in Sat. Eve. Post 16 July 16: He’s been all over the country [...] but with all that practice he’s still a jeep.
1941		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 20 Dec. 9/6: The jeep has started again to creep, to pester you and haunt your sleep.
1970		Current Sl. V:1 16: Jeep, n. An inexperienced Air Force enlisted man or officer [...] —, adj. inexperienced.

3. (US black) a drunkard.

1947

M.H. Boulware Jive and Sl. n.p.: Jeep ... Whiskey head.