This might be my fault. I was in Charlottesville for a few months about 16 years ago doing some work for a startup, hanging out in my off hours with a group of sorority girls who had worked for me in London when I’d been an impresario.
I say (or rather, said, as this episode made me very conscious of it) “hmm, curious” almost reflexively when working on something. They aped me. They partied, they spread the meme. Within a week I was suddenly overhearing people in cafes and gas stations going “hmm, curious” and by the time I left town I felt like I was living in a poorly written Monty Python sketch (or perhaps a Lovecraft bit), as an epidemic of “mmm, curious” had taken over the townspeople and the UVA student body. The latter all then went home at the end of the year, towards the end of my stay there, and spread it to every corner of the U.S.
When I went back a year later, they were all still at it.
I guess this ties in with the whole “teenage girls introduce new language” piece a few weeks back.