When you have an especially bad day, sometimes all you want to do is scream. But, if you scream at people, you could strain your relationship with them; they may feel more distant towards you, despite their efforts to sympathize with you. You could also run the risk of being sent to a psychologist. I personally was sent to a psychologist, but I didn't enjoy it. I learned that the best place to scream is into your pillow, not at others. Not only does the pillow not get upset, but other people in the house won't hear!
Screaming can also be considered annoying. Then comes the question of what to yell into your pillow.
Essentially, you can yell anything you want to. If you want to cuss or curse, you can! Actually, this has actually been encouraged to relieve stress; a study showed that cussing helped alleviate negative feelings.
Screaming into pillows can not only very helpful, but also therapeutic. I suggest that you try it out.