incumpetent
Da state of being brainless and/or naive regarding sperm and its related aspects/properties/effects, such as making a huge mess, implicating someone in a crime, spreading STDs, getting a girl knocked up, etc.
Willie and Monica sure were woefully incumpetent when they carelessly got love-juice on Monnie's dress and thus revealed that there had been some hanky-panky going on between them.