I had an idea for some posters in Transit with advice fo n00bs, in the style of WW2 posters.
"If you're text is green,
It can be seen!
If you don't want a spy,
Use the key 'Y' "
etc.
EDIT: I prefer:
"If your text is green,
The Aliens spy,
If it shouldn't be seen,
Always press 'Y' "