This is indeed really random It's these kinds of emoticons, where something completely unexpected happens, that I love the most.

Overall, the shading and pixel art look really nice. There are a few things that bug me about it though. The choice of colors on the emotes are a bit too dark, in my opinion. I think it might look better with a bit brighter palette. Also, the smile on the green one goes a little too close to the eye on the right, making them blend together and resulting in it being hard to distinguish between where the mouth ends and where the eye starts.

The animation, however, is excellent and very smooth, and the idea is brilliant, so overall you've done an excellent job!