Instructions
Go north from the Living Room to enter the Backyard. Press "X" to bring up your item selection menu. Use your control stick to scroll through the options, and then press "A" to select the Squirter.
Look around in the Backyard for a small puddle or pool or water. These are common and can be seen from far away. Press "A" when you are near water to suck it up into the Squirter.
Go to the flowers, and look for a shriveled frog laying on its back. Press the "A" button while facing the frog to spray it with your Squirter. Spray the frog three times in all to wake it up.