I had no idea this was a thing until the morning after I woke up from my first time partying around people who were using it. Someone took a leak and I hear, "Hah! Yep, there's the good ol' orange K piss," and I couldn't help but be surprised that it sounded like they were laughing at the fact they were pissing blood.
I should clarify - nothing against ketamine in small doses recreationally, just take care of yourself.