Hanging out with someone who knows all your secrets, accepts your family for all their quirks and eccentricities, and shares the same inside jokes seems to be the best of both worlds. A friend who saw you through braces and the awkward puberty years, drank a beer with you in college, and now comes to throw some horseshoes in the backyard is rare indeed.
More importantly, you're grown and you're hanging out because you want to - not because your moms are making you! When your relationship goes beyond the history and you begin making new memories together is when it really gets good. I hope our kids continue these friendships that are forged in family.