What is st and tm on instagram?

Right then. These are just common bits of text-speak you see everywhere.

'ST' is simply a shortcut for 'something'. So if someone says, 'tell me st', they just want you to tell them something.

'TM' usually means 'text me' or 'message me'. It's an invitation to slide into their DMs for a private chat. They are essentially just slang terms to make typing a bit quicker. Cheers.