I jacked off with one friend in high school. In college it never happened, but thinking of one college roommate, it almost did and I wish it had. After college and before I got married, while watching porn with a friend, he wanted to beat off and I said what the hell and joined him. We did it several times again after that first time, but without the porn stimulus.
It has always been fun to jack off with help from someone I'm in a relationship with, like a bf or gf or, now, my wife of course, but those casual encounters with another guy were in some ways more exciting. Since getting married, I haven't jacked with a guy. It would take more effort to make it happen now, and probably wouldn't be the same as those spontaneous times back in the day.