Drunk mechanic, Joao Leite Dos Santos, clambered into a spider monkey enclosure in his local zoo only to find they were not in the mood to play.
The fiercely territorial animals were angered by his decision to join them at the Sorocaba Zoo in Sao Paulo, Brazil.
Amused tourists watched as the topless mechanic swam over, having had a few too many drinks on Sunday afternoon.
It was then that he was mobbed by at least six spider monkeys and he began screaming in pain as they bit him. One of the monkeys went for Dos Santos's wrist, while another bit his right elbow and shoulder.
Stumbling back through the water, he waded away from the attacking animals, his blood colouring the water around him.
He lay on the ground in pain for several minutes, bleeding heavily from the deep bite marks in his arms, after zoo workers hauled him out over the enclosure fence. Eventually he was taken to hospital.
He may yet face criminal charges.