The bach's night usually organised by the best man while the
hen's night by the maid of honour or bridesmaid.
I didn't have bridesmaid for our wedding but one of my female
friends organised a mini party for me anyway.
It doesn't have to be a crazy night. It can be a bowling session
with a group of friends and have nice dinner afterwards.
Over here, you can hire a stripper for the bach's/hen's night if
you wish to. When my female got married, her sister organised one
for her. I didn't go to her hen's night though as I was trying to
cut cost at that time for our wedding. 
