I guess becasue it is Halloween.
Most clubs organize Halloween nights
for the customers to dress up in all kinds of costumes.
Some clubs offer good prizes for the most
creative costumes.
It is a lot of fun.
Even if you don't dress up in costumes,
you can still go to have a few drinks, dance
and watch all the interesting costumes.
It is one of the most popular occasions for a night out.
You can check any montreal web sites
or local newspapers for the clubs.
Halloween falls on Friday this year
so there will be Halloween nights
on both Friday and Saturday depending on the clubs.