Ask Me About Mustache Mode (known as Mustache Mode in the Game of the Year Edition) 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, which will make some types of zombies have mustaches. If the player types it correctly, the achievement will be earned.
- The Game of the Year version of the game simply calls it "Mustache Mode." It is still unlocked in the same way.
- It is the only achievement related to activating a code.
- It is the only achievement directly referenced by the handbook. A poster advertising it is among the items in the "Some stuff I found on the street" section on page 134.