sponcrastinator

transitional n. If you're the kind of person
who attempts to get ready to do something important and then
you say:"The hell with this, I'm gonna do something else
instead," your friends are likely to describe you as a
Sponcrastinator, which means that you behave in a naturally
Sponcrastinatious manner without prompting, performed or
occurring as a result of sudden inclinations without
premeditation or external stimulus.