This doesn't require two people or constant jumping until you're sore. In Ep 8 once Cookie Monster says its time to start jumping, you jump until the game automatically goes to something falling from the tree.
Note that you can stop jumping at any time before that to force it to the falling sequence, but in order to get the achievement you have to let the game decide when you have done enough.
You can stop once it cuts to the branch, then start up again when Cookie says to. There are four jumping parts.
I got this in one try. My legs are not that sore, it didn't take me ten minutes. At most each jumping segment might take 30 seconds.