Since you've been physiologically capable, what's the longest period of time you've gone without sex/wanking...
My longest time is probably this:
I went on a family holiday to the states about 15 years ago and decided to refrain from wanking the entire time i was away (3 weeks). My head was strong, but alas, my body was not so. I had a wet dream after about 2.5 weeks, whilst sharing a bed with my older brother. I told him about this last year and he was quite flattered.