This appears in levels 14 and 15 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 watermelon will still appear after the second rock has dropped. However, if you die before collecting the watermelon 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 watermelon appears in the middle of the gameplay area (where you start the level). As soon as you pick it up, this achievement will pop.
If you're having trouble with this game, don't forget that you can turn on level select in the settings by pressing
before you start the game with
. All you have to do is get to a level once, and then you can select to start from that level any time after that.