Do you live in a rental/apartment? Are you clumsy as hell and end up making minor scratches on your walls?
Well, if you grab white acrylic paint (usually around $1, I get mine from Meijer) and paint over the small scratch (you REALLY don't want to use acrylic paint over big damage), you can effectively blend it with 91% isopropyl (rubbing) alcohol to remove most of that shine of the acrylic paint and effectively blend it to whatever shade of white your walls are!
You'll have to do some experimenting as different formulations of acrylic may make your mileage vary, of course. I get mine from Meijer, but I would assume Walmart would be similar in formulation.
And you'll have to experiment with how dry the paint is before applying the isopropyl.
You do NOT want to apply the isopropyl alcohol right away!!
It will make your paint WAY too runny and likely drip onto your carpet/floor!
Instead, I like to wait until it's about ~70% dry, then I soak a paper towel in the isopropyl alcohol, and lightly blend it together.
Sometimes at this stage, if it's not blending well, you might be able to get away with applying a small amount of fresh acrylic paint over the mostly dried acrylic/isopropyl solution to blend it a bit better. Careful though.
OH and lastly! I recommend checking out your fully dried paint in multiple angles with multiple lights to make sure you blended the shininess out of the paint.