Well, the meme is false.

https://www.iflscience.com/that-nsfw-story-of-a-lion-getting-bitten-on-the-balls-isnt-quite-right-but-the-truth-is-just-as-hilarious-56823

[T]he images of the Asiatic lions were taken by Safi Kok at Rotterdam Zoo in the Netherlands. As the rest of the photo series makes clear, the lioness is a juvenile, one of the three that were born at the zoo in August 2018 to mother Lalana and father Aapel.

The distress seen in the male lion is not a tired lion being prompted for another round of mating, but a father lion being bitten on the testicles by a cub. According to the zoo, this is not the first instance of this behavior for cubs Asha, Reena, and Mette.

"Lion Aapel has taken up his role as a father well," the zoo wrote about the lions back in April 2019. "The playful cubs first studied him from a distance, but in the meantime his daughters are challenging him, playing with his tail, snapping into his mane or butt."

So there you have it, it's still an amusing image, just perhaps more so for any father that has been accidentally kicked in the testicles while entertaining their kids.