Bananas

You get this pet from the WoW TCG in the set "Through the Dark Portal"

In February 2021, during Blizzconline, it was announced Bananas would be a reward from its World of Warcraft Charity Pet Program:

With the upcoming World of Warcraft Charity Pet program, we’ll be supporting the medical humanitarian aid organization Doctors Without Borders/Médecins Sans Frontières (MSF) and we’re making some improvements to how the program works. During this campaign, you’ll be able to donate any amount you wish directly to MSF. We’ll be tracking your contributions during the donation period, and once a pre-set goal has been reached, we’ll make Bananas the monkey available for everyone playing modern World of Warcraft as a thank you, whether you were able to donate personally or not. In addition, if we reach an additional stretch goal, everyone will receive a second pet Daisy the sloth. She’s an all-new pet that you can carry with you everywhere you go right on your back! Your donations during this program will go to MSF’s COVID-19 Crisis Fund to support MSF’s global response to the pandemic and its consequences (donations will be collected by MSF-USA.)

Check back on the official World of Warcraft site in the near future for more details.

Bananas used to be a rare TCG pet, in March 2021 Blizzard made it available to all current players. However, the availability will be for a limited time. To receive the pet it must be claimed; you can do so via your Blizzard account on the Blizzard website - once you have successfully made your claim, Bananas will be in your companion pet list the next time you log into the game.