Green’s Dictionary of Slang

a term of endearment.

1909		Decatur Dly Herald (IL) 12 Sept. 15/4: She was the littlest girl [...] ‘Snookums,’ Denby had called her.
1914		Eve, Dispatch (London) 19 Mar. 4/4: [of a pet dog] [picture caption] Snookums has been digging up someone’s crocus.
1926		Nottingham Eve. Post 24 Nov. 1/3: [of an escaped pet monkey] Snookums was caught last night at Latimer-road.
1928		R. Carr Rampant Age 223: ‘Party,’ she shrilled. ‘Birfday party for my Snookums!’.
1932		J. Dixon Free To Love 127: He’s as tame as a pet poodle. Calls her ‘dearie’ or ‘snookums’ or something sappy.
1953		Dly Mirror (London) 10 June 2/3: My husband’s pet nam for me is ‘Snookums’.
1961		Mad mag. Sept. 18: While snookum’s widdle bottle is heating up, we’re going to comfort him [etc.].
1986		Eble Campus Sl. Mar. 9: snookum – the object of one’s admiration and affection; someone to snuggle up with and cuddle: John’s my l’il snookum.
1996		P. Beatty White Boy Shuffle 9: Snookums [...] would you please pick up some tomatooes, a head of lettuce, and a little nigger child.
2002		R.G. Barrett Mystery Bay Blues 247: All right snookums [...] Would you like your teddy bear too?