wonderstick Share definition Flag penith. often 13 inches long, and whoever has one is the CHOSEN ONE. Harry Potter has a wonderstick, for he is commonly called the CHOSEN ONE, so he must have a 13 inch long penis. wonderstick by mrs. wonderstick January 14, 2012 0 0 Get merch Get the wonderstick mug. Buy Now — $32.95 See more merch