Do not upset U.S. teenager Calvino Inman too much - or he may see red. Doctors have been left baffled by the 15-year-old Tennessee teenager, who cries tears of blood.
They come three times a day, often with warning, and can last for up to an hour - leading some classmates to fear he is possessed.
Calvino and his mother have now appeared on national TV new programmes in the hope that exposure with bring an explanation to the stigmata-like medical mystery.
He said: 'Sometimes, I can feel it coming up, like a tear. I feel my eyes watering.
'Sometimes, it will burn as it comes out.'
Pictures and video show red teardrops rolling down his cheeks and leaving a bloody trail as his eyes brim with more blood.
Calvino added: 'I've been called possessed by almost all of my friends.
'I guess I'm used to it now. At first, it kind of hurt my feelings.'
The first time the tears came, Calvino's terrified mother Tammy called emergency services.
She said: 'The scariest thing in my life is when he looked at me and said: "Mum, am I going to die?"
'That right there broke my heart.'
Appeal: Calvino and his mother Tammy are hoping doctors can provide them with a proper explanation for the freaky tears
So far, Tammy has taken Calvino for an MRI, ultrasounds, a CAT scan and to see several specialists. But as yet, none has been able to explain the medical mystery.
Ophthalmologist Dr Rex Hamilton said Calvino could be suffering from a rare condition known as haemolacria, which means 'bloody tears'.
'That is just a descriptive term of the manifestation of the bloody tears,' Hamilton told television show Good Morning America.
'It says nothing about what's causing that. It's a one-in-a-million kind of condition.'
Meanwhile Ms Mynatt said she hoped the television exposure would lead to a cure - or an explanation, at least.
She said: 'More than anything, I just truly want somebody to say they've seen this.
'I just please want somebody to help my baby. That's all.'
Cases where people bleed through their eyes or their skin are uncommon but not unheard of.
Last year the Mail reported on Twinkle Dwivedi, 13, who has a disorder which means she loses blood through her skin without being cut or scratched.
The teenager has to undergo transfusions after pints of it seeped through her eyes, nose, hairline, neck and the soles of her feet and sometimes her condition is so bad she wakes up with her entire body covered in dried blood.
Medics in India believe the youngster's condition is an extreme version of a rare blood platelet disorder for which they cannot find a cure.
Her condition meant her blood is dangerously low in clotting particles, which makes her blood watery.
In fiction, the 2006 James Bond film Casino Royale features creepy villain Le Chiffre, played by actor Mads Mikkelsen, who has a bleeding tear duct.
See video of his bloody 'tears' below
Blood apparently wells up in the teenager's eyes as a TV news film crew record the phenomenon