So, given this context, what is your opinion? Is this a death threat? "I will piss on you...".
Not sure but for sure it's dirty. Not sexy too.
On a serious note: Say this is a death threat. What worse can happen to you unless your identity is public and the guy has some real balls. This is an anonymous place and nothing is there to harm you physically. I do not guarantee mental healthy though.
It is not clearly a threat because no one knows as here unless when you connect your account in your real social media account or you did not made a pseudonym. I think it is just an exaggerating statement to the user. We all know that some of us are keyboard warriors. They are only warfreak when they handle the keyboard but they are really coward in real life.
I can say that if it is harmful when the user mentioned your real name with a death threat.