"that" is highly problematic and "this" and "it" and sometimes "yes" and "no" as well.
You have no idea what I am talking about? That's exactly the issue :) placeholder words often occur in short chat/text messages and while the sender thinks the reference is clear, receivers often do not. Better to be a bit more verbose and expand the reference, make it explicit. In network programming it's known that stateful messages, depending on content from earlier messages, is complicating things.
