Halloweek occurs once per year. It is a set 5-7 days where you will see girls galavanting about in themed costumes, with equally enthused guys running around.
It gives everyone a perfect excuse to get trashed and go to a theme party on a tuesday.
Meant to be taken advantage of.
Early morning lectures are optional during this week.
Old friend: "Why are you so trashed, don't you have class tomorrow at 8?"
You: "YEAH BUT ITS HALLOWEEK!!!"