Hangouts has changed significantly since the beginnings of Android. Originally known as Google Talk, Hangouts has now evolved into a nearly ubiquitous messaging and calling solution, but there are a few additions that need to happen first.

One surprising omission in current Hangouts application is Stickers support. For those who don't know what a "sticker" is, they are small GIF images that can be found in places such as Google+ posts. Although Google hasn't yet added them to Hangouts, XDA Recognized Contributor Quinny899 has, and it comes in the form of the aptly named Stickers for Hangouts.

Your chat recipients don't need to have Stickers for Hangouts installed to see stickers you send them. What's more, this application can be used in two ways. In the first way, you add a sticker by selecting Add Photo and then Pick a Sticker. Alternatively, you can use this as an Xposed Module. Doing so adds a direct option to the attach menu in Hangouts. Naturally, if you go down the Xposed route, you need to have a rooted device and have the latest version of Xposed Framework installed.

You can find this app/module in the original thread. Go there keep the spice alive in your Hangouts conversations.