No it's a bit more serious than that I can give 2 particularly good examples
one was after a family dinner at a restaurant we were all walking back to the car and my brother said I looked like I wanted to kill someone when I asked what he meant my mother agreed with him and wanted to know what was wrong when all I was doing was just thinking about how to make one of the foods we just ate
The other was when I was helping my best friend pack a Small storage unit his school provided him to use while he and his wife took a Small break from school immediately after the birth of their first kid it was looking pretty full but we were only about halfway done so I sat and was thinking how we could rearrange it to fit more stuff in it when he came back and he saw me he tensed up and cautiously asked me if I was alright I responded yeah just thinking about how to fit more stuff in there and he visibly relaxed and said to me "good you looked like you were going to kill someone"
I guess my natural expression is probably something like this
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