onii-kun Share definition Flag Someone bigger than you calling you "Little kid" or to girls "Little girl". Hey onii-kun, what did your parents say when you said you had a new brother? "Make sure he's not gay?" onii-kun by urmumgeylol629 May 17, 2018 0 0 Get merch Get the onii-kun mug. Buy Now — $32.95 See more merch