I do get nervous in crowds because I don't like people standing too near me. Also I get upset if I feel I am in anybody's way because it makes me feel like I'm a clumsy oaf who always gets in people's way, so it makes me get upset. I have no problem with being touched but I do hate when strangers touch me if I am in their way (some people do, especially old ladies. It makes me feel like a 3-year-old).
But when I'm feeling agitated, upset and anxious, it's always on the inside, and can be slightly noticeable through facial expressions, otherwise hardly noticeable at all if people aren't really looking (which in most cases they aren't when in supermarkets). I don't do any unusual body movements that are odd to NTs, like hand flapping and all of that.
But being in crowds has it's good and bad points. The good points are I don't feel compelled to make eye contact or say hello to anyone (with some exceptions depending on the context, like saying thank you to someone letting me past or greeting somebody who I know or being served by the cashier, etc). But when in quiet places and you're passing somebody, you feel more compelled to have to make eye contact and say hello to them, and for some reason saying hello to a stranger always makes me feel uncomfortable - again depending on the context.
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Female