A photo posted online by Waraschaya Akkarachaiyapas has caused outrage as it shows her cupping the testicles of a tiger at a Chiang Mai zoo in Thailand.
Locals have accused the tourist of humiliating the tiger, saying she had no right to touch its genitals.
''This is so rude. The tiger did not allow you to touch his privates. You have no right to do that,'' Phorntip Siracha posted in response.
Another respondent said Akkarachaiyapas could have paid the ultimate price had the tiger reacted.
"If the tiger had reacted angrily it could have attacked you.''
In previous years, some zoos in Thailand have been accused of sedating animals to allow interaction with humans, but so far there's no suggestion this could have been a factor in this incident.
Pirom Cahntama, a staff member at Tiger Kingdom, said all visitors are monitored while interacting with animals and are not permitted to touch the genitals of any of the animals.
"We do not allow tourists to grab the tigers' testicles but they are allowed to touch any part of the animal's body as long as our specialists are present," Cahntama told media.
"From now on, we will make sure that no visitor will ever be able to touch this part of a tiger's body again."