One step further would be to make an intentional unique grammatical mistake that only you know of, or a spelling mistake, or both.

Henceforth, if I find any intentional mistakes, you will be executed - mark my words!

Examples of intentional "mistakes" designed to gain an advantage:

He included some intentional mistakes to make the experiment "a little more interesting".

A favorite sport, of course, is fooling the sensor, and the system is not above making an intentional mistake.

"It was not an intentional mistake," Mr. Rosenberg said, adding, "these are complex accounting issues."

Noted for intentional mistakes, and purposely performing notable errors.

A nonritual skirt of these people features other motifs with intentional mistakes, a design called "My mother-in-law dreamed it."

All mistakes, intentional or unintentional, should be laid upon my doorstep.

Note that this does not apply to "intentional" mistakes, such as l33tspeak.