Space, the final frontier! Golden Egg #22 is hidden behind the slingshot platform on level 1-3 of Summer Pignic. You’ll need to fling the white bird backwards and drop an egg bomb on the grass directly behind the platform. You have to hit it just right for the Golden Egg to pop up, so if you don’t do it the first time try again.
Note, this is a two part video. The first part shows how to find the Golden Egg and the second is a walkthrough on how to pass the actual Golden Egg level.