Sic Nabo Share definition Flag Verb. A sexual act in which one partner repeatedly slaps him or herself in the back of the head until rectal constriction is achieved. See Auto-Donkey Punch. "Dude, she totally Sic Nabo'd herself to orgasm. My orgasm, that is." Sic Nabo by metrolu December 3, 2011 0 0 Get merch Get the Sic Nabo mug. Buy Now — $32.95 See more merch