The microwave is one essential appliance that has saved many hungry moments simply by transforming cold leftovers into piping hot meals in minutes. You know things can get hot—chances are, you’re part of a generation that bit into a hot pocket way too soon and learned the hard way to let it stand one-to-two minutes as the package directed. But despite their undeniable convenience, there are certain things that have no business on that warm, rotating plate. Some are obvious, while others may come as a surprise. Here are 10 things you should never put in the microwave.

1. Metallic Objects

This might be another one that falls into the learned-the-hard-way category. If you’ve ever absentmindedly left your fork on the plate while reheating, you could tell by the sparks flying that it’s not a good move. Just a few moments longer, and it’s a mistake that could cost you your microwave, or worse, start a kitchen fire.

2. Plastic Containers Not Labeled “Microwave Safe”

If you’re still in your plastic era, make sure they’re clearly labeled safe to microwave. Not all plastic containers are created equal, and subjecting the wrong kind to the microwave can result in a gooey mess or even release harmful chemicals into your food. Stick to containers labeled “microwave safe” to avoid a plastic apocalypse. Or, make a bold change and go for the glass containers or innovative food storage like this one from Caraway.

3. Styrofoam

It’s so tempting to not dirty a dish and reheat that foam container your takeout came in. Unfortunately, it’s not meant for the microwave. Heating up this material can cause it to melt, releasing toxins into your food and making a mess you’ll be scrubbing for way too long.

4. Eggs in Their Shell

Fun fact, you can cook eggs in the microwave. But, hardboiling them while still in their shell is not the move. The pressure will build up inside, causing it to explode with a loud pop. Stick to boiling eggs the old-fashioned way, or at least crack them into a microwave-safe bowl.

5. Paper Bags

Popcorn in the microwave is a classic movie night snack done right, but tossing that unpopped bag back in for a second round can be a recipe for disaster. Paper bags aren’t designed to withstand the intense heat of the microwave, and they can easily catch fire, turning your cozy movie night into a fiery inferno.

6. Hot Peppers

Ever heard of pepper spray? Well, microwaving hot peppers can have a similar effect on your sinuses, except it’s your entire kitchen that ends up feeling the burn. The oils released by microwaving hot peppers can irritate your eyes and throat. It’s worth it to save yourself the pain and chop peppers as usual.

7. Breast Milk

For all the new parents out there, this one’s for you. Microwaving breast milk might seem like a quick and easy way to warm it up, but it can result in uneven heating, creating hot spots that could scald your baby’s delicate mouth. Not to mention, microwaving can destroy the valuable nutrients in breast milk. Soak it in a warm water bath instead and keep your little one’s mealtime safe and nutritious.

8. Grapes

When sliced in half and subjected to the microwave’s energy, grapes can produce tiny sparks of plasma, creating a miniature light show in your kitchen.

9. Nothing at All

Ever been so hungry that you absentmindedly press the “start” button on the microwave without actually putting anything inside? We’ve all been there. But running the microwave empty can damage the internal components and shorten its lifespan. Plus, it’s a waste of energy. So, next time you find yourself in a hangry haze, double-check before hitting that start button.

10. Your Phone

Do you remember the rumor a while back—or maybe it was a TikTok Trend—where people were saying you could charge your phone by putting it in the microwave? Yikes. Not only is this not true, but it can destroy your phone by smoking your battery, melting electronic parts, or even causing an explosion. In fact, you’ll want to keep your phone away from the microwave in general since it can interfere with Bluetooth signals.