Locks you out from viewing the site for a specified duration after looking at HN for up to a specified amount of minutes.
from the FAQ:
In my profile, what is noprocrast?
It's a way to help you prevent yourself from spending too much time on HN. If you turn it on you'll only be allowed to visit the site for maxvisit minutes at a time, with gaps of minaway minutes in between. The defaults are 20 and 180, which would let you view the site for 20 minutes at a time, and then not allow you back in for 3 hours.
I've been on this site for maybe 6 years and only just recently created an account. If I see the same problem this one will go too.