From several different sources:
From the Oreo people. I’m not sure what the significance of June 25th is; this year, many pride parades were on Sunday the 24th, and Stonewall Day (commemmorating the Stonewall Inn riots in NYC) is the 28th. But the visual is nice.
Oreo is a trademark for a popular sandwich cookie by the Nabisco division of Kraft Foods. Since its 1912 introduction, Oreo has become the best selling cookie in the United States, through the 20th century and into the 21st. It is distributed under the brand Christie in Canada. (link)