Answer:
From your question, I assume you have somehow put onions into your nose. Of course, if you have done this, you now know that onions in the nostrils is not a good idea. They have a pungent smell, they make your eyes and nose water, and overall cause quite a bit of problems! Unfortunately, onions would not easily slide back out of the nose once they are pushed in. So, just one onion -- even a little onion slice -- is reason to go to the doctor right away. The good news is, doctors made a special tool to easily pull onions (and other objects) out of the nose, ears, and mouth/throat. Often, it only takes a couple minutes to get them out.
So, if you haven't told already, go tell your mom or dad what you did and ask them to take you to the doctor. And remember from now on, you shouldn't put anything that's bigger than your elbow into your nose, ears, or mouth.