Why is "Per my last email." funny?

Office-speak

Who it channels

The office worker who has run out of patience but not out of politeness.

Where it comes from

A line of corporate email etiquette — technically neutral, universally understood as a frosty "I already told you this."

Why it lands

It is an insult in business formalwear. Everyone in an office knows that "per my last email" means "read the thread, genius," and the joke is the thin, transparent layer of professionalism over the irritation.

How to drop it

Reminding your flatmate, again, that the rent is due: "Per my last email."