I have this one aliased to mkcd, but yours saves an extra character. I like it!

add in exec functionality and you've got xkcd!

I call it "mcd"(for make and cd) on my windows cmd and bash shells

Zsh has the "take" command which accomplishes this.

Correction: Zsh does not have the take command. The Oh My Zsh add-on has the take command.

(Lots of us don't use OMZ)

Very interesting - didn't know that. I always install OMZ after zsh.

Didn't know that! thank you

I use `mkdir -p DIRECTORY_NAME && cd $_` in bash which is not as concise but still DRY.

This is the sort of DRY that is more dogmatic than helpful, IMO.

Quite.

DRY is a good guideline but a rubbish rule.