This footage - seen 20 million times in less than 24 hours - shows a heroic doctor who spent 37 minutes sucking urine from an elderly passenger's blocked bladder mid-flight using nothing but a plastic tube and an empty wine bottle.
The selfless act was recorded on board China Southern Airlines Flight 399, which was bound for New York's JFK airport from Guangzhou, capital of Guangdong Province in South China.
According to reports, cabin crew made an emergency broadcast asking for medical assistance from any doctors on board at roughly 1:55am local time on 19th November.
The elderly male passenger could not relieve himself and was sweating heavily from discomfort, but the flight was still six hours from New York and any potential standby paramedics.
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Doctor Zhang Hong, who is head of vascular surgery at the First Affiliated Hospital of Jinan University, identified himself and offered to help.
Present was also Hainan People's Hospital vascular surgeon Xiao Zhangxiang, reports said.
Doctor Zhang told Chinese media later: "The pensioner's abdomen was bloated, he could not sit still and was sweating a lot.
"He was going into shock and may have suffered a risk to his life if we didn't tend to him urgently.
"His family said he had a history of prostate enlargement, so we suspected this was causing urinary retention."
The medic said there was about 1 litre of urine in the passenger's blocked bladder, which was at risk of rupturing.
With no medical equipment on board, the doctors improvised a makeshift catheter using a plastic tube from a portable oxygen cylinder, a syringe from the plane's first-aid kid, a plastic straw from a milk carton, and some tape.
After receiving consent from the man's family, Doctor Zhang inserted the device into the patient's bladder, but he discovered the syringe needle was too thin and could not effectively extract his urine.
Risking infection, Doctor Zhang decided to suck out the patient's urine using his mouth and the tube.
During 37 minutes of treatment, Doctor Zhang reported extracted roughly 800 millilitres of urine from the relieved patient.
Footage taken in the plane's galley shows the medic repeatedly spitting urine into the empty wine bottle during the life-saving procedure.
He added: "There was no other way. I didn't think too much about it. I only wanted to help him extract the urine retained in his bladder.
"Saving lives is a doctor's instinct."