What's the worst advice you were given that you actually followed?

I just got a new car a few months ago, and I dented it last week by running over a chain sealing off a closed recreational parking lot in the mountains. My friend has absolutely no automotive expertise, but she's a horrible driver and gets into lots of accidents so I decided to take her advice to "just pop the dent out with a mini plunger thingie" in hopes that the bumper would look like it used to.

Now there's a 6-inch dent where a 2-inch dent was and I spent a whole hour looking silly, plugging away at my car with a plunger. A cop even stopped by my apartment and asked me what I was doing... I guess he assumed I was trying to vandalize someone else's car and I had to show him my keys to get him to believe me.

That, and aside from heaping mayo, egg, and avocado on my hair last week because someone told me it would repair split ends (which it didn't, and it stained my carpet and favorite silk robe) is probably the worst advice I've ever gotten and followed.