Let's start off with something both educational (you'll learn a new word that you can use at parties -- to get kicked out) and incredibly weird, that uses the female body somewhat like a lampshade. Welcome to this list.

A vaginal photoplethysmograph is essentially a flashlight that's used to illuminate the capillary bed of the vaginal wall and the blood circulating within it. It then uses that to measure stimulation.

It consists of a clear acrylic, rod-shaped device, a light source and a light detector. It's one mighty, hefty flashlight that only scientists, vaginas and unemployed test subjects ever get to see.

The light is used because scientists can determine the amount of blood flow in the vagina by the amount of light that is backscattered, which is measurable. This light is thought to be directly related to the transparency of engorged and unengorged tissue which in turn can indirectly measure sexual arousal.

So basically, the redder the better.

Shaped like a tampon, the device can be self-inserted or applied by anyone willing to do it. pornographic movies are usually the erotic stimulus in these tests.

So the test goes Show porn > Flashlight in Vagina > Check for Color > SCIENCE!