This is an anonymous place and nothing is there to harm you physically. I do not guarantee mental healthy though.
It may be but certain language and posting habits are prohibited, including;
"
8. No threats to inflict bodily harm, death threats"
Even if the possibility of actual harm is excluded, it doesn't encourage discussions if anyone is allowed to use any choice of words and some sort of order has to be established.
So, given this context, what is your opinion? Is this a death threat? "I will piss on you and burn you".
You actually didn't give the context (like whether it was posted in another language and meaning was lost in translation), but taking the words literally; it is a threat to inflict harm and breaks the forum rules.