In-game icon
Shake or Shaking is an action performed by pressing the appropriate button when available.
Shaking is an action that causes multiple items to fall out of trees. This speeds up the collection process for items like 
Dead Branches or 
Cocos that otherwise require collection one at a time by climbing up the tree and then back down.
Mechanics[]
You have to climb the tree to an appropriate height for this action to appear. Not all trees can be shaken.
You then have to press the appropriate button at the correct time for the shaking action to be successful. If you don't shake hard enough, the items will not fall from the tree.
If there are no more items in the tree, you can shake the tree as much as you want but nothing will happen.
Once shaking starts, there will be an option to press a button to Stop Shaking. Pressing this button will stop the shaking process.