For this achievement, you have to spin attack two cannons during the level 'THAR HE BLOWS!'
on the map 'SALTY WHARF'.
This is a dingodile stage for reference.
Progress through the level until you get to the part where dingodile will say ''You smell good enough to eat''
. There will be a pirate ship in the distance, and on the path to the right will be a bunch of crates so you know you are in the right place. There will be two cannons pointing towards the camera at an angle. All you have to do is spin attack both of the cannons to unlock the achievement. It is that simple!
Video guide for reference:
Hope this guide helps, let me know if I should change/add anything to this guide rather than downvoting it :)