They would call this " dead pools" , and he would take that as his name, as a kind of joke.
他们会称之为“死侍”,他就把它作为自己的名字,当做一种玩笑。
英语百科
Dead pool
A dead pool, also known as a death pool, is a game of prediction which involves guessing when someone will die. Sometimes it is a bet where money is involved.