The billionaires took a lunch break at a nearby Dairy Queen — which Buffett's company acquired in 1998 — in April. The pair donned aprons while participating in a standard employee training.
"We learned how to work the cash register, greet guests, and make a Blizzard (including the proper way to serve it, 'Always upside down with a smile!')," Gates, 63, explained in a blog post last week. "I think I may have been a quicker study than Warren in the Blizzard department but ... you can judge for yourself."
A nearly 4-minute video posted on Gates' blog showed the businessmen getting ready to work.
"This is just a sample of our competence. If you think this is bad, wait until we really get into action," joked Buffett, 88, after the two accidentally put on the wrong name tags.
The competition to serve the best blizzard — and cone in general — was a rocky road.
"Who had the bad luck to draw me?" asked Buffett as he handed a customer a small vanilla cone, drawing laughs. "If you want anything, later on, it's on me."
A Dairy Queen employee stood beside the pair as they worked the cash register.
"A double banana split? You're a real man," Buffett repeated a male customer's order.
Buffett offered to put his hand out to collect customers' money, joking that he'd leave Gates to do the "high-tech stuff."
After finishing their shift, Gates sat down with Buffett and asked the Dairy Queen owner why he decided to buy the ice cream chain.
"I've known Dairy Queen all my life ... When they were contemplating selling, they thought of Berkshire," Buffett replied. "We made a deal and we lived happily ever after."
The Dairy Queen trainer, only identified in the video as Zach, said the pair "could have done better." But in the end, he said he "would hire them."