I was on a "route discovery" ride to BART in Antioch and I was riding in the bike paths. An hour and 12 miles later I noticed that my front tire seems softer than usual. I stopped and discovered a goat head stuck on the tire. I pulled it out and immediately flatted. No problem, I have a patch kit and a spare tube if necessary. Replaced the tube, reinstalled the tire and reached for my pump on the frame.
Wait! Its not there. Reached for it in my jersey pocket. Nope, not there either. I forgot the pump at home. I then reached for the cell phone, which was thankfully there, and made the call of shame to the wife to give me the ride of shame home.
Now, I have a pump attached to every bike I have, just in case.