Give the Latin name of the roach and then launch into a comprehensive natural history of the species. They'll be bored immediately and want to change the subject.
When I was fifteen I thought girls would be impressed with science and philosophy stuff like I was.. Nope, you were right, they changed the subject every time! But I was smitten, I figured that later I could interest them in stuff that really mattered, so I let them lead the conversation, figuring I could steer the conversation into something more interesting than spray starch later on. Nope, not happening. Turns out, men weren’t much more interested in talking about that stuff either. Maybe one in a thousand, like Solomon said..
But I wish you were around to give me dating advice sixty years ago.