Send ghost messages and set invisible nicknames on Facebook Messenger.
Facebook Messenger has a strict validation filter. If you press the spacebar, the blue "Send" arrow remains inactive (greyed out). To bypass this, you need a character that Messenger recognizes as a letter but renders as empty space.
The Hangul Filler (U+3164) works perfectly for this in 2026. It allows you to create a large empty bubble, confusing your friends.
You can hide your name inside specific chats using the Nickname feature.