If you are of a certain age, you can peg Rosanne Barr's 'ha,' or even Johnny Carson's chuckle, Chris Rock's blast-laugh, etc. We could all come up with many examples; a favorite would be Mr. Jones's doing Darth Vadar.
My first passport (I'm only on the second) had amendments to my signature on the official first inside page. I was conscientious to note for the state departments that I acknowledged a seemingly sudden change in my "legal" way of representing myself with a pen. It went from having most of the 10 letters to a mere stylized version of my initials, a joined set of two marks.
I don't know why.
There was no circumstance to make it so, such as having to sign 100 Christmas cards or business letters. Suddenly, one of my driver's license had A, and the next and subsequent documents B.
People remark on it, more often than I'd think is warranted. I have never commented out loud on anyone's "john hancock," though I'm very interested in calligraphy, especially as it pertains to "the signature," be it on a painting/drawing/etc. or on a legal document or just a letter. The latter in this three-part example-chain is quite rare, I know. But I continue to study people's signatures the way a dog studies smells, perhaps. I just don't have any conclusions to draw.
So I do things like save cards from mom, dad, grandparents. Their signatures (only the lattermost) have changed over the years. Like their land-line home-phone voicemail messages, the signatures of my parents have not moved as long as I've known/seen them (with the exception of my mother's — but I never read her name when she used to sign it using mine/my father's; the font is the same).
My signature has not changed in at least a decade. I have an alternate one I use for business letters; it is in part so I can't be "stolen," but mostly so it looks more human, thoughtful and readable.
One of my college-era diaries has a frontpiece where I would record my new signatures. Some were experimental, some were actual documentation of a rapidly changing personal history. I'm pretty sure I could revert/resurrect any one of them.
My laugh of late reminds me of my sister-in-law's. This would be the younger one, my brother's wife. I think I have a subconscious desire to mimic her genuine happiness. It's consciously known now — look, I discovered it.
No one I know has ever remarked upon my laugh. I have heard things like "don't smile enough," "are you having fun?," "what are you thinking?," etc. My laughs have always sounded outside of my head, and I am curious what they might mean to anyone else. They are supposed to sound like music or at least be usefully infectious.