I'm trying to look up the official name of those envelopes they use to send tax info. The ones with the perforated edges, that fold out and the envelope becomes the form. I've been rephrasing this question to search engines several different ways. So far, the AI has given me several dozen Amazon links to purchase manilla envelopes in bulk, but the only once has it even tried to give me the name of something.

That thing which it named was "intergluteal cleft."

The intergluteal cleft or just gluteal cleft, also known by a number of synonyms, including natal cleft, butt crack, and cluneal cleft, is the groove between the buttocks that runs from just below the sacrum to the perineum[...]

I am quite certain that this was not the container that my W-2 arrived inside of when I received it. The AI revolution ain't here yet.