Talking with CNN's Laurie Segall in an interview aired on Sunday, Zuckerberg described the multi-billion dollar negotiations with WhatsApp co-founder Jan Koum and how his dog helped make the deal happen.
My dog Beast, I think, is actually the secret weapon here," he said. "It was a tense moment and Jan was like, All right I need to think about this."
Zuckerberg said the room was silent for a few minutes before Beast walked in, "kinda confused."
"He's like, 'Whats going on? These two guys are just sitting here silent," the billionaire recounted.
"[Beast] then walks up to Jan and jumps in his lap," Zuckerberg said. "And then Jan starts petting him and a second later he's like, 'Okay, I think were good.'"
Beast continues to be a beloved member of the Zuckerberg household, with his own dedicated Facebook page and a penchant for getting dressed up for big events like Halloween.
In October 2016, Zuckerberg posted a picture of his daughter Max with the woolly pup and announced that her first spoken word was "dog."
Things with the WhatsApp co-founders, however, didn't end up so swimmingly.
One of the private messaging app's co-founders Brian Acton left Facebook in September 2017 after clashing with Zuckerberg and COO Sheryl Sandberg over discussions of monetizing the service. Acton told Forbes in a subsequent interview that the two Facebook execs "represent a set of business practices, principles and ethics, and policies that I don't necessarily agree with."
Amid the Cambridge Analytica scandal, Acton shocked many by joining in on the #DeleteFacebook movement, tweeting : "It's time. #DeleteFacebook."
WhatsApp's second co-founder Jan Koum whom Beast hopped onto during negotiations left Facebook in August 2018, also over pressures to monetize the app and frustrations with "big company" culture, according to a Wall Street Journal report .
By leaving Facebook before their stock options fully vested, it was estimated that Acton and Koums would forego a combined $1.3 billion.