After nearly 5 years of marriage and 8 years of being together, there's "playing doctor", and then there's the just as common "playing actual doctor" :
"Make sure to cover your hair with a towel or something, so the peroxide doesn't bleach it. Although that would look pretty funny..."
"Right, yeah...okay, I'm supposed to use a cap-full of peroxide."
"All the article says is peroxide." *lays on side, thinks* Hey, can you do this? I'll probably spill it everywhere."
"If I must...what's the bowl for?"
"It says to drain it into a bowl."
"A paper towel would work just fine."
"But it says to use a bowl."
"Whatever. Here we go."
"It's the fizzing! And popping! It makes my back spasm! Doesn't that happen to you when you have stuff in your ears?"
"I can't look at your face right now." *puts towel over beloved wife's face, walks away*
*twitching and cringing* "Let me know when it's been 20 minutes."
"You're gonna go the full 20?"
"I don't want to have to do this twice!"
"It's been 20 minutes."
"...Can you get me a paper towel? I don't want to dump peroxide on my face because I don't understand physics."