Real mode, Mod R/M and SIB byte encoding weirdness, REX prefixes, 80-bit floats, parity flag, hard-wired registers for shifts/multiplies/divisions, builtin CRC32 over the wrong polynomial, Pascal calling convention support, binary-coded decimal, high halves of 16-bit registers, MMX overlap with x87 floating point, etc. etc.
This is completely off topic, but I've seen things like the "^W^W" a few times before, and I don't know what it means.
Is this a weird encoding mismatch thing? is it from some editor/system that people instinctively type? Is it from some other forum which has a strange markup syntax for something?
'^W' is what would appear instead if you weren't in a readline/emacs editor, but instead a dumb line terminal. Thus, leaving '^W' behind makes it look like you didn't realize what you just corrected is still visible.
It's a joke. I've now explained and ruined it.
I've used Linux daily for like 15 years now, and I know about control characters, but since I never really used emacs (or readline beyond the copy+pasted command here or there) I just completely missed the meaning.
This readline behavior follows a Unix tty driver. I'm not sure off the top of my head which one introduced it. I don't think it was on xenix but am pretty sure some 4.x bsd had it.
In Unix line editors it is traditionally used to mean 'erase the previous word'.
See also documentation for ASCII (http://www.robelle.com/smugbook/ascii.html for example) for origins of ^C, ^D, ^S, etc.