ssssssssssssssssss!
I was typing up printer specs for a book just now, and I had to type the following (in three different form fields):
S5 satin silver or similar
snug
CMYK (<--which is pronounced see-em-why-kay)
I don't move my lips when reading or writing, but this little sequence proved to me that apparently my tongue at least mimics what my brain is telling my fingers, because I felt a urge to start hissing like a punctured bicycle tire.