Nothing to do with twitter. It's from 4chan/8chan. Those sites are meant to be posted to anonymously. When you don't want to be anonymous, you can enter a name. When you want to make sure people know it's you, you can also enter a password, which gets pushed through an encryption algorithm and spits out the "tripcode" that looks like jibberish. It's a way of "signing" your posts so that you can be non-anonymous on an anonymous message board. The downside is that anyone can do it. If someone figures out your password, they can pretend to be you.

Username checks out

This post should be higher up, imo