In 2001, my friends dared me to go out with the leaders for as long as I could and hang on. I was in decent shape at the time, so running 5min pace for a few miles was not a problem -- but I sure wasn't in shape to run that pace for MORE than a few miles.
Anyway, by 5mi, I was about 10meters from the lead pack and the pace caught up with me. I kept running and my legs felt like jello, slowing to about 7:30 miles. Then just after the 10k mark, I messed my pants. I think it was due to the torrid pace I set at the beginning of a marathon, never having run that fast for 5mi much less at the beginning of a 26mi run.
So, I'm running for another 8mi with s*** coming down my leg. It was actually somewhat interesting since it gave me some entertainment while the other runners commented. I was in such pain that I needed SOMETHING to take my mind off the cramping. Problem is, I started chafing around the s*** and then my dick started bleeding like Uta in '96.
Needless to say, Newton was HORRIBLE. By then, my nipples were as red as a SWEET VW Jetta, boyz and my quads were non-existent. I walked from 18mi into the finish and came across the line in Copley Square JUSt before they closed the course officially.
Funny thing is that I now drop a doogin in my trousers at the gun every time I toe the line for a marathon. It makes for some interesting conversation along the run.