A long-tailed macaque passed out for 10 hours due to a caffeine overdose after he drank a cup of strong coffee on Sunday (5 November).
The cup was left hanging inside a plastic bag on the motorcycle of a tourist in Bangkok's Bang Khun Thien district when the 6-month-old male monkey nicked it.
Immediately after drinking the strong brew, the baby monkey fell sick and passed out, The Nation reported.
The incident was reported by a Facebook community page named, "Khon Rak Ling Hua Jai Kraeng" (Thai for Good-hearted monkey lovers).
Members of the community were alerted by a food vendor at the Khun Kala Floating Market that a small monkey appeared to be sick.
Community members along with a veterinarian took the monkey to Doctor Raiwin Pet Hospital. He was put on a drip of saline and carbon until 3am local time (8pm GMT) on Monday when he appeared to recover.
Once the doctors were confident that the little animal had recovered, it was released back into the care of its troop.
The group has warned people about the dangers of feeding processed foods to macaques.
In May, a morbidly obese macaque nicknamed "Uncle Fatty" by locals in Thailand had to be taken to a weight loss boot camp.
Uncle Fatty weighed 27 kilos, which is almost double the standard weight for the animal. They usually weigh 8-10 kilograms.
He was taken to a facility to help him lose weight, where he was encouraged to exercise and was put on a strict diet of fresh fruit, vegetables, and lean protein. He was released back into the wild after completing the three-month long boot camp.