The longest I ever went was a week. I was in a situation where I just could not do what I wanted to do for ages. One night I dreamed I was searching for my porn and getting more and more pissed off when I couldn't find it. Eventually I did find it, only to wake up at the same time as a fountain of cum shot everywhere. The one and only wet dream of my life.
Ever since that night I made sure that I would never go that long again - which I haven't. Always managed to fuck or masturbate long before the week was up. In fact I can't imagine going more than a day without shooting off. I just don't know how anyone can go weeks without at least a nice wank now and then. In fact, now sounds better than then.