knuckle dump Share definition Flag Knuckle Dump: Ejaculation through masturbation. This girl was so dirty she asked for the old knuckle dump on the chin. The circus is in town people and there WILL be face painting. knuckle dump by Kuric May 1, 2008 0 0 Get merch Get the knuckle dump mug. Buy Now — $32.95 See more merch