Hacker News Reader

I'm curious, are they used anything like memes that you can easily send more than once?

Not sure what you mean by "like memes". They are just funny images with thousands of variations that you can send. If you're going to sleep - send something cute that shows it.

Some examples http://www.line-stickers.com/

The only thing I could see that would potentially top this would be talking animated emoji....The feces one comes to mind specifically

It it talks, it takes too much time to parse, and it becomes too specific.

Pictures, maybe with a max 0.5 sec animation are okay, and no sound. (At least that's my hunch.)

So basically emojis?

Sure, if emojis could be infinitely extended with arbitrary images and were sent as their own messages instead of being embedded inline with other text. Replying to another message with a sticker also fills the role played by reactions on Facebook Messenger.