Downloads Happy Hippo Stickers for iMessage How to use iMessage Stickers: • Tap the App Store icon alongside the message box in iMessage • Tap the icon on the lower left corner and then the plus icon to access the App Store for iMessage. Tap Manage tab and find Happy Hippo Stickers to add it. • You can peel and place them on anything in your conversation – bubbles, images, or even other stickers.