cockblunder Share definition Flag A cockblunder is a giant mistake usually caused by overlooking a very obvious situation or circumstance. "You put your penis in the toaster?!?! That's a cockblunder if I've ever seen one!" cockblunder by Krin Gabbard July 29, 2005 0 0 Get merch Get the cockblunder mug. Buy Now — $32.95 See more merch