Whack-a-Monty is an action minigame from the game New Super Mario Bros. DS. The minigame's name is akin to Whack-a-Mole, whose gameplay it borrows some of its own elements from.
In this minigame, the player has to tap on the Monty Moles that pop out of the holes. Upon their defeat the Monty Moles give one point. They will also stack up in piles on the top screen. However, humans can sometimes pop from the holes, and if they get struck, the humans take three points away to retaliate.