I've had some strange stims (maybe tics?) come and go over the years. Since balding, I've taken to drumming my fingers on my bonce (I've been a bass-player for years, so rather forcefully sometimes); and I don't know what the hell I ever used to do with my hands before I grew my beard out - I just can't leave the damned thing alone some days. There's another, which I can only describe as "gurning", which I have done for as long as I can remember, but it only seems to pop up unexpectedly at random, sometimes with months in between - I just have to pull the most extreme facial expressions that I can for a few seconds, and I've never discerned any specific trigger for it (if someone told me that my eyebrows just get bored sometimes, it would be as believable an explanation as any other.)
If there are no particular thinking patterns associated with it, then it may be something along similar stimmy lines (stress tends to increase stimming in general, of course). Other kinds of tics, I don't know enough to comment about.
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