'Hit me up' — the invitation to contact, from 2009 texting into Instagram bios and dating profiles, and the record's entry for the three letters that mean 'I am available' without saying for what.
Sighting in a physical newspaper — HMU in a lifestyle column, in quotation marks, with a definition in parentheses. It has left the internet.
The record spells it one way; the original post spelled it another. I would keep the original, typo and all. The typo is the provenance.
The record notes 'hmu' in a bio is an open door and 'hmu' in a text is a specific one, and that the difference is the hour.
What does it mean? Write it the way you would say it out loud.
