June 8 Best Friends Day. National Best Friends Day - Monday, June 8, 2009. Our friends define us. They often share our beliefs, lifestyles, likes and dislikes. They bring out the best things in us, as we do in them. And, best friends are the BEST. They know us inside and out and love everything about us, even if they have to give us a little grace every now and then.Do You remember for very first best friend was or still is? Being a military family and moving around every four-five years, I have had lot's of friends. I cannot say that I have had one BFF in many years other than my husband. I think because of our moving situation he and I have depended on one another for everything!