This appears in level 1 after dropping two rocks. To drop a rock, dig under it, and then move out of its way so you don't get squashed by the rock.
Note: Dying between dropping rocks 1 and 2 DOES NOT reset the 'count' of rocks. The carrot will still appear after the second rock has dropped. However, if you die before collecting the carrot when it's on screen or if you don't get it before it disappears, you will have to restart the level, as it won't reappear if you do rocks 3 and 4.
The carrot appears in the middle of the gameplay area (where you start the level). As soon as you pick it up, this achievement will pop.