Green’s Dictionary of Slang

(US) constr. with beating, walloping, etc. a thorough, severe beating; also as adv.

1835		W. Otter History of My own Times 5: [H]e, in the plenitude of his goodness, got hold of me, and gave me a genteel wallopping.
1835		W. Otter History of My own Times 79: I found out my old lady, she got right genteely boozy.
1837		W. Johnson diary 5 Aug. pub. as William Johnson’s Natchez (1951) 186: there I found Little——— ——— with a Muscovia Duck in the act of [blank] He was frightend very much—I took him and gave him a Genteel whiping.
1893		R.M. Collins Chapters from the Unwritten History of War between States 320: [N]othing but our lame leg kept us from giving him a genteel thrashing for thus insulting us.