flipcode
nounUK /ˈflɪpkəʊd/
US /ˈflɪpkoʊd/
A secret set of letters or numbers that you flip around to hide a message.
The kids made a flipcode so only they could read their notes.
OTHER MEANINGS
2. A quick trick or flip you do with a code to change it.
He used a flipcode to swap the letters in his name.
3. A special code used in a game to make things flip or turn.
Type the flipcode to make the screen spin around.
4. A hidden pattern of numbers that flips back and forth.
The lock opened when she entered the flipcode 1212.