To do Pre-NNN is to do NNN before the month of November to prepare for the challenge. If you fail Pre-NNN then you can still participate in the actual thing. You can do Pre-NNN on the 20th of Oct.
"I don't know if I'm ready for NNN this year, so I'll be doing Pre-NNN as a head start."
"My father did Pre-NNN last year and it helped him get through the actual thing. I think I'll be doing it too this year."
The opposite of having the itis. When one has pre-itis, it is also known as having the munchies or just hungry right before taking part in eating a big meal.
Man I haven't ate for 13 hours. I'm fixin to have 2 large pizzas and 2 litre coke. I gots the pre-itis.