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.

Dejagoo is the strange feeling that you've been in this sticky situation before. It is dejavu due to goo. Usual symptoms are shivers down once's spine followed by disgust, especially if actual goo is involved.

A week on which October 31 usually falls within one year. It starts with costume craze and ends with tons of candy on sale. Some also consider smoking halloweed.