1. vulgar slang Literally, to pass urine that is tainted with some amount of one's blood. A kidney injury during a football game had me pissing blood for nearly a week. It turns out that I was pissing blood because of prostate cancer.

2. vulgar slang, dated To exert oneself to an extreme and exhausting degree. We've been pissing blood trying to get this project finished on time. The foreman said he's have the workers pissing blood if that's what it took to get the house built before winter set in.