If you've ever had a dog or a cat you'll know that they have a tendency to just hang around at the back door of the house after being let out.
They either moan for ages, make tons of noise or just get bored and lay down until someone lets them back in.
Often you might not know they are there at all. Then you open the door, they come darting in and they give you the fright of your life.
If you know that feeling spare a thought for this woman in Colorado who thought that a dog was at her door, only to find out that it was a huge bear who charged at her.
Watch the hair-raising incident in the video below.
According to the description on Viral Hog's YouTube page, the woman claims that the bear was anxious because she was close to its cubs.
I opened my front door thinking it was a dog.
Turned out it was a female black bear mother who was very agitated that I was between her and her cubs.
She briefly charged at me, sending me flying back into my house.
Thankfully it appears that she managed to get away unscathed but you can bet that she will have a quick peek outside the next time she hears some rustling outside.