You have been best friends since grade school, but this moment changes everything.  The second you saw him in his tighty whiteys, you boned up instantly.  There is no chance of hiding it, your 10" meat is poking up past your waistband.  Before your buddy leaves this basement, he will have taken a load of your jizz in his ass, willingly or not.  Your best friend just became your cum rag, he just has not realized it yet.