I've had two sets of friends that I've jerked off with. One is a friend I've known since middle school. He and I discovered early on that we share a lot of the same interests in sex and we sorta help push each other's perviness to the next level. We're both completely straight but I think that being able to say some of the perverted things that we do (about females) while we jerk off actually adds to the horniness that we feel. I'm very open about sex and jerking off generally and it's always fun to just relax and do what comes naturally when you're looking at vaginas. I've also masturbated a few times with my old roommate. With him it was a matter of convenience and straight up male bonding. We got horny talking about pussy, slipped in a porn, and jerked. I think in both cases it's only added another dimension to the friendship.