"I get the box open and there's just bubble wrap everywhere, but under the first layer I see a picture and my jaw. Just. Drops," she wrote.
She had uncovered an image of a smiling Gates wearing a festive hat and sitting in front of a Christmas tree.
She immediately called her husband, who was at work when the package arrived. Speaking quietly, she confirmed that he could speak with her before she shared her news.
"And I said 'Bill Gates is my freaking Santa!" she wrote. "I worried him too much, it took a second for it to sink in, but oh MAN I was excited and flipping out!"
The well-known philanthropist and richest man in the world sent a slew of gifts to Aerrix, including a pair of video game-themed mittens for herself and a smaller set for her dog, an Xbox One and a Cajun cookbook.
"Merry Christmas to all y'all out there, and to Mr. Gates, who has the biggest heart and really knows how to treat a girl to some video games," Aerrix wrote. "I'm just blown away by his generosity, which went even further than all these gifts because he submitted a donation to Code.org in my name, to give more students the chance to learn computer science."
See the full unboxing on RedditGifts.