User Card Background

Hi, I wanted to ask you guys a question, what is a user card back ground? As seen here:

I don’t know, but you could upload a picture to find out. Let me know if you do this, 'cuz I’m curiöus.

It’s used for when you click on someone’s avatar.

Ok, thanks you!!!

You! You just returned?

For just nsfw? We’ll flag your posts!

The chickens learn some english i think

This is @ChickenInvadersFan72. He is, just insane! We need flag his posts!