The Do no Smurf achievement is worth 50G and is unlocked by playing a level and not freeing any Animal Friends.

This can be done on level 1-1 and very easy to achieve. Just take your time. Basically what you have to do is reach the end of the level without attacking any of the animals. You can get hit by them. But is one dies, you will need to start the level again. You can use any Smurf for this. Alternatively you can play through the level on another account and when you get to the end of the level, sign a second controller in with you main account and finish the level.

Here is a video guide: