| Ask Me About Mustache Mode|
Enable Mustache Mode.
Difficulty: Very easy
Ask Me About Mustache Mode is an achievement the player can earn if they purchased Plants vs. Zombies through Steam. To earn this achievement, the player must simply type "mustache" or "moustache" while playing the game or in the Main Menu, making the zombies have mustaches. When the player types it correctly, the achievement will be earned. The player can earn this achievement anytime in the game.
- The Game of the Year version of the game simply calls this as "Mustache Mode". It is still unlocked in the same way.
- Ask Me About Mustache Mode is the only achievement related to activating a code.
- The player can earn Ask Me About Mustache Mode without the Tree of Wisdom.