What does it mean when my urine is really hot?

Not much: The temperature of urine will be at normal body temperature. If you have any questions, you should see your doctor.

Hot urine!: Urine will be at body temperature when it leaves your body. Depends on what you mean. Burns or stings when it leaves your body? Most common cause would be an infection. Other causes could be a kidney stone, vaginal infection, STD. The best thing would be to let you doctor test a sample.

You have a fever: Your urine is always the same temperature as your body immediately after you void it.