The act of thinking about football, soccer, golf, dead puppies, your mom etc etc during sexual intercourse causing a disruption in your exitement level and thus, not cumming as fast as you normally would (i.e. 1 minute)
Joe- I was about to cum while having sex with my girlfriend, but i had to resort to coitus procrastination since it had only been 45 seconds since penetration.
Mark- Awesome bro! I will start coitus procrastinating from now on!!