Nothing strange about that you may think, until you realise that the "ass" in question is not being used as a slang term for a butt.
Nope, unfortunately in this instance it's referring to donkeys.
I saw a reference to this on an episode of The Grand Tour and assumed it was just a joke, however an internet search has shown otherwise.
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"Yes, you read that right. In the northern Colombian town of Cartagena, adolescent boys are having regular sex with donkeys. This tradition is widely known and accepted in parts of Colombia as a rite of passage for many boys to become men. Fathers will often take their young boys out to teach them how to have intercourse with the farm animals."
"As Colombia is an extremely catholic nation, pre or extramarital sex is extremely frowned upon. So using Donkey’s is just a surprising loophole for horny youth. They also believe that having sex with donkeys will make their penises bigger as well as prevent them from becoming homosexual."
Nope, unfortunately in this instance it's referring to donkeys.
I saw a reference to this on an episode of The Grand Tour and assumed it was just a joke, however an internet search has shown otherwise.

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Insanely Bizarre Sex Cultures You Won't Believe Exist

"Yes, you read that right. In the northern Colombian town of Cartagena, adolescent boys are having regular sex with donkeys. This tradition is widely known and accepted in parts of Colombia as a rite of passage for many boys to become men. Fathers will often take their young boys out to teach them how to have intercourse with the farm animals."
"As Colombia is an extremely catholic nation, pre or extramarital sex is extremely frowned upon. So using Donkey’s is just a surprising loophole for horny youth. They also believe that having sex with donkeys will make their penises bigger as well as prevent them from becoming homosexual."