How long can you keep opened hot dogs in your fridge?
"I don't know? if they look bad or smell bad," says Katherine Oldham of Tyler.
How about luncheon meat?
"Maybe about a week until it is all wrinkled up," says Jeannete Brown of Whitehouse.
But using that rule of thumb may leave you sick.
"Once you open up something that is processed, the general rule is that it is good for 3-5 days," says dietician Regina Dick.
Opened food is exposed to air and bacteria, so those expiration dates no longer apply. Things like hot dogs, ground beef and sausage will only last 3 days after opening. Luncheon meat can have an even shorter life span, especially if it came from the deli.
"A good rule of thumb, the more handling the food has been involved with is exposed to more germs, and the more germs the shorter the life in the fridge," says Regina.
Milk and mayonnaise may also not last as long as the sell by date because they are opened often. Eating any food once it starts to spoil or become infected with bacteria can lead to food poisoning. 76 million people get food poisoning every year -- 5000 die from it. So Regina says be safe, not sorry, and throw your food out 3 days after opening, no matter what the date says.