I guess a good example was when I was naive enough to visit my wife's family on Thanksgiving Day. Her sister led this ritual thing where everybody was given gifts in turn and everybody else's attention was focussed strongly on whoever was receiving their gifts at the time, even to the point of some of them capturing it in close-up on their phones for uploading to social media. I can usually just about hide it when somebody gives me something I don't want, and I can usually blend into the background and get ignored when I'm feeling uncomfortable in company, but this time there was no hiding place.
Nobody said anything about my expressions or body language, but under those circumstances I couldn't believe my negative feelings were going by unnoticed, which further fed into my embarrassment. I had to use a lot of painful self-control to get through it without ruining the occasion for them, and they must have noticed I didn't like the procedure. The whole thing was horrible. But my wife is the only one who has any idea what I went through, and I don't think even she understood it very well. Americans are used to Thanksgiving rituals, but to me it was a disturbing culture shock. I suppose the cultural difference was partly responsible, but I think if I'd not had ASD then I'd have been able to cope with it much better. I'd have been able to fake enthusiasm and empathise with their reverence for ritual.