Imagine this: you’re stopping by your parents’ house while they’re on vacation. Naturally, it’s the perfect opportunity to raid their freezer for some tasty treats.

But as you open the door, hoping to find ice cream, you notice something odd—a frozen cup of water with a coin sitting on top. What in the world is that doing in the freezer? Read the article to find out why your parents are actually advanced people because of using this lifehack.

Around the globe, we are experiencing a rise in unusual weather patterns, signaling a clear message from nature: it’s time to treat the planet’s resources with greater care. This shift includes unexpected heat waves in typically cooler regions, cold spells in warmer climates, and severe weather events like hurricanes, tornadoes, and heavy storms in places usually known for calmer conditions.

These events can often lead to power outages. Fortunately, there’s a clever way to check if a power outage occurred while you were away: simply freeze a cup of water, place a coin on top, and keep it in your freezer.

Have you ever come home from work or a vacation to discover that the time on your digital clock is incorrect? You might assume, “There couldn’t have been a power outage.” But if there was, it’s impossible to know how long the electricity was out. It could have lasted long enough for food to thaw, spoil, and then refreeze when the power came back on—leaving no obvious signs that anything had defrosted.

Even if you’re just taking a quick weekend getaway, it’s a good idea to use the old “coin in the freezer” trick. While leaving your house, put a coin in a cup of water and put it in your freezer. When you get back, check the coin. If it stays on top of the frozen cup of water when you return, it’s good. But if it drowns, it’s bad because it means the power was out long enough for your food to thaw and potentially spoil.

Food that has thawed and then refrozen might look fine, but it could be contaminated with bacteria if it was at room temperature for several hours or even days. According to USDA guidelines, food left unrefrigerated for more than two hours can develop bacteria that cause illness if consumed. That’s why this simple, no-cost trick is a smart way to check if your food might be spoiled.

Use a clear glass cup or a piece of glass or plastic Tupperware. Fill it with water and let it freeze completely, uncovered. Once frozen, place a coin on top of the ice. If you come back and find the coin halfway down, the freezer must have lost power long enough for the ice to partially melt and then refreeze, which likely means your food is still safe.

However, if the coin has sunk to the bottom, it indicates the freezer was off long enough for everything to thaw completely, potentially reaching room temperature. In that case, it’s best to discard any food in the fridge and freezer.

When it goes about food, especially frozen food, some extra caution will always be useful. And here’s how you tell visually that your frozen food has gone bad.

Ice crystals in the packaging

• This means water molecules in your food have made their way outside, towards the colder parts of the freezer. It’s not a danger to your health, but it isn’t exactly tasty either. The food loses a lot of its moisture and this has negative effects on both the taste and the texture.

  Change in color

• This goes mostly for meat. For example, if you notice a steak is starting to get a little grayish instead of its usual red color, it’s time to throw it into the bin. The gray color is a sign that it has almost passed its expiration date. The same is true for vegetables: if they’re losing their fresh color, it’s best not to eat them anymore.

  Meat juices

• If you notice that the frozen meat in your freezer has spilled some pinkish meat juices, you know you can no longer eat it. These juices indicate that the temperature of your freezer isn’t stable and that the meat has thawed and has frozen again. Throw it away!

  Smell

• When the frozen food is smelling a bit funky, that’s your sign to throw it off in the bin without thinking much.

And here’s yet another lifesaving tip from TikTok. A woman explained why other women should never turn on the light immediately after they return home.