So basically during the past year or two I’ve caught my (24f) sister (31f) talking to herself throughout various times of the day. I wouldn’t normally think it’s concerning, but she is not simply talking herself through a task ex. saying “I need to do xyz later.” She is instead incoherent and would sometimes come up to me to blurt out nonsense words in strange accents while laughing even when I tell her to stop it, mostly because I’m getting older and now have killer headaches. 

For example she would be in the kitchen cooking and start saying random sentences with curse words out of now where. I caught her saying things like “I’m gonna fuck you up” and “shut the fuck up bitch”. Sometimes it’s just gibberish sentences with an angry/over excited tone. 

She also has the habit of blurting things out randomly so I have no idea if this is just a nervous tick but the violent sounding context when she talks to herself plus the fact that she’s already an angry, impatient unpredictable person is freaking me out. She’s always randomly blurted things but the talking to herself part only started 2-4 years ago. Is this a real concern?

Edit: she also makes a lot of noises when doing certain tasks. When showering she says “wooo” and “ahhhh” maybe 100 times. It’s very loud and awkward. Just now she kept saying “wooo woo woo” while drying, and then yelled at the pet cat. She said “move you bitch”. She screams at him angrily everyday.