There was a period of a few months when I was first learning about web apps where I saw "i18n" multiple times. The first time I came across it, I tried to sound it out:

i18n -> I-one-eight-n -> iwonation

I was already a couple of rabbit holes deep at the time and didn't have the mental capacity to look it up and wrap my head around yet another new concept.

"Oh boy." I thought to myself, "One more word I've never heard of, probably representing some complicated CS concept."

I was so annoyed when I finally found out what was going on.