I'd completely forgotten about the mundane definition of "boner": a mistake that causes embarrassment to the person who makes it. I have boners almost every day. Why, just yesterday at Starbucks I grabbed the wrong coffee cup and then loudly complained about the whipped beverage that I'd gotten instead of coffee!!
Was also contemplating the term "bonehead", with my favorite application being one Arnold J. Rimmer (yeah, I'm gonna make y'all look that one up).