Green’s Dictionary of Slang

(US) conceited, self-opinionated, snobbish.

1928		E.C.L. Adams ‘Joe’ in Nigger to Nigger 38: An’ dere ain’ nobody as discountin’ as a big-doin’ nigger when he is up in de world.
1928		J. Peterkin Scarlet Sister Mary 98: Sho, I’ll back-jaw you as much as I please. Who is you to be so big-doins anyhow?
1930		DN VI 79: Big doin’s [...] Conceited, haughty.
1934		J. Peterkin Roll, Jordan, Roll 197: On fourth Sundays her fine clothes and big-doings walk made her look like some stranger-woman from town.