Green’s Dictionary of Slang

(US black/Harlem) to eat fast and greedily; thus swobble-mouthed adj., eating greedily.

1926		E. Walrond Tropic Death (1972) 94: Young Briton, red-faced, red-eyed, red-haired. Yellow teethed, dribble-lipped, swobble-mouthed, bat-eared.
1944		D. Burley Orig. Hbk of Harlem Jive 148: Swobble—To eat hurriedly, greedily.