Sirius and James would text harrys kids while they were at hogwarts and when James Sirius starts using abbreviations, they try it too. They abbreviate EVERYTHING. So much that their messages make no sense. Remus new how to use abbreviations and understand James and Sirius' tho so we're all fine.
Sirius: Hey, mfns hrudt?
James Sirius: Huh?
James Sirius: Moony? What does mfns hrudt mean?
Remus: padfoot messaged u?
James Sirius: yup
Remus: it means, my favourite name sake, how r u doing today, I believe.
James: hello, gs!
James Sirius: Gs?
James: Grandson!
James Sirius: ...no...please no
Inspo from messaging my dad and using the abbreviation, tbh, then proceeding to spend an hour explaining it...