Inspired by mood rings (dark blue means I'm romantic -- meet me in the back of my Explorer in ten!), this is a video of Youtube couple EvanAndKatelyn making themselves a thermochromatic temperature sensitive toilet seat (and lid!). It takes some trial and error but the final result is pretty impressive, and I wouldn't hesitate to sit on that provided it's completely black before I do because I don't like being reminded somebody's ass was just where my ass is about to be. It's like sitting down on a warm toilet seat -- it's unsettling. Especially when that warm seat actually turns out to be your girlfriend's lap because you just zombied your way into the bathroom and sat down without looking. She still jokes me about how loud I farted because I was so startled. "I swear he caught air!" she's always telling new friends at parties.
Keep going for the video, but skip all the way to 18:15 for the finished product.
Thanks to rainbowsaurus, hands down the most colorful, and my favorite, of all the sauruses.