Evolutionary biologist John Logsdon returns to explain the amazing diversity of sperm design, and its connection with mating behaviour. And Scientopia blogger Scicurious joins us to discuss some of our favorites from her Friday Weird Science archives. We'll talk about everything from the antidepressant properties of semen, to smelly semen, to testicle receptacles, and so very much more. Here are links to all the Friday Weird Science posts that we discussed with Scicurious. Do your balls hang low? Your balls can't take the heat from your laptop. A tote for your scrote, a recepticle for your testicle. Rats in pants....