Menagerie Message was the title of a note that Ronald Weasley sent to Harry Potter in August of 1992, when Harry was at Diagon Alley shopping with the Weasley family. It warned Harry that the Magical Menagerie salesman would kick out anyone he caught sneaking around in his shop. This note proved useful as Harry was, at the time of receiving the note, attempting to retrieve Trevor from the Magical Menagerie for Neville Longbottom.
You'd better be careful in the shop.
Don't let the miserable old shop wizard catch you, or he'll throw you out.
- Harry Potter and the Chamber of Secrets (video game) (First appearance)