If you use a Resource Pack with custom splashes, the first splash on the list appears with a weird symbol in-game.

Steps to reproduce:
Create a resource pack with custom splashes.
Make 4 or 5 different lines of splashes on the splashes.txt.
Open up Minecraft on that resource pack until the first splash on the list pops up.
It has a weird symbol next to it: a ZWN BSF in a box

Below is an example picture. In the resource pack used in the picture, the first splash is "Beef Shower!"...