It is a biological truth that in most cases of human canoodling some modest amount of various and sundry bodily fluids are produced. (Indeed, many female humans in the author’s aquaintence have had occasion to note that some male specimen seem to produce excessive saliva when mating rituals such as “necking” are undertaken. What is with that, anyway?)
Well, ladies and gentlemen, imagine your horror should you find that your mate had the habits of Engystomops pustulosus (formerly known as Physalaemus pustulosus.) When mating, the eager male frog positions himself atop the female and starts to pulse rhythmically (not to say monotonously, though some lady frogs might complain on that account). As a result, the female releases a foam producing solvent which the male’s gyrations froths up into a giant, floating foam nest that protects the fertilized eggs “from dehydration, sunlight, temperature, and potential pathogens until the tadpoles hatch.”
Very creative. And very… well, unsavory, frankly. But if one is a Tungara frog, one might find such foamy emmissions quite provocative. And the author suspects that should she look hard enough, she would find internet porn for that.