National Ask a Stupid Question Day is Sept. 28, but it's also usually commemorated in schools on the last school day in September. The day was created back in the 1980s by teachers who wanted to encourage kids to ask more thoughtful questions in class. The idea behind it? The only way to learn is by asking. As Stephen King wrote, "The only stupid question is the one you don't ask."

In honor of this most important holiday, we've compiled a list of six "stupid" questions that really aren't stupid at all.

1. Can you sneeze with your eyes open?

An Asian man sneezing Your eyes close when you sneeze as a reflex, but you can control it. Maybe. (Photo: deeepblue/Shutterstock)

The answer to this one is no — for most people — but the question of why you can't do this is an interesting one. There's an oft-told myth that if you sneeze with your eyes open, they'll pop out of your head. While this may be a fun anecdote to share with your 7-year-old nephew at the next family reunion, it's not true. Your eyes shut when you sneeze, much like your knee jerks when it's tapped: it's a reflex, and it's one that we can't control. Find out more about the anatomy of a sneeze here.

2. Has it ever rained frogs?

Man with umbrella while it rains frogs Ribbit ribbit! It has rained frogs before! (Photo: Martina Osmy/Shutterstock)

Quite surprisingly to many, the answer to this one is yes! The phenomenon, though it sounds fake, happens when a waterspout occurs (basically a tornado over water). The wind picks up the water (and whatever happens to be swimming around in it) and carries it in its vortex until it loses pressure and releases it again, in the form of rain. Usually, the frogs don't survive the unfortunate "relocation." More common than frogs? Their aquatic neighbor — fish.

3. Why do humans have 2 sets of teeth?

Young boy missing front tooth We have to grow into our adult teeth. (Photo: Liukov/Shutterstock)

Have you ever stopped to think why we get a whole set of teeth when we're little, lose them and then get a whole new set? According to the BBC: "The reason you have two sets of teeth probably comes down to size. A full set of permanent teeth would be too big to fit into a young child's mouth. So milk teeth act as a bridge until the jaw is large enough to accommodate a full set of permanent teeth."

4. Why do we hiccup?

A woman with red hair holds her breath Hiccups are the results of a less-than-smooth contraction of your diaphragm. (Photo: Piotr Marcinski/Shutterstock)

Here's another bodily phenomenon that people don't think about much: hiccups. Hiccups happen when your diaphragm is irritated, such as when you eat too fast and take in extra air, drink carbonated drinks or eat too much. A hiccup emerges when your diaphragm contracts jerkily instead of smoothly like it's supposed to, causing a sudden intake of breath that's stopped when your vocal cords snap shut, causing that characteristic "hic!" noise.

5. Do animals dream?

Ginger cat sleeping in cat bed Animals like cats may not dream in the same way humans do, but they do experience mental images while sleeping. (Photo: Alena Ozerova/Shutterstock)

It's very likely, says Hugo Spiers, Ph.D., an experimental psychologist at the University College London. From the UCL website: "The researchers monitored brain activity in rats, first as the animals viewed food in a location they could not reach, then as they rested in a separate chamber, and finally as they were allowed to walk to the food. The activity of specialized brain cells involved in navigation suggested that during the rest the rats simulated walking to and from food that they had been unable to reach." A similar study was done with cats back in 1959, where researchers concluded that although animals may not dream like we do, they are indeed seeing images during REM sleep.

6. Why do we have an appendix?

Many researchers believe that our appendix is a prime example of a vestigial organ — an organ that we no longer need but still have in our bodies. Some research suggests the appendix may be the epicenter of our immune system, housing "good bacteria" that can help us fight off infection. There are studies that show having an appendix can help tremendously when the gut is populated with unhealthy bacteria. So if you still have yours — bravo!

There you have it, folks. Six stupid questions that — on further investigation — aren't really stupid at all. Got another question you want answered? Post in the comments below.