Why are they called stag and hen nights?

Question

I know it's something to do with turkeys ie male turkey is a stag and female is the hen, but whats the connection between going out and getting wasted before you get married and a turkey? Please don't answer by explaining what a stag do is, I know what they are. I just would like to know why they are named as such.

Answer 1

It may surprise you to learn that the word stag  hasn't always meant "male deer".  In Middle English, stag  could mean the adult male of any animal, especially if castrated .  In the 19th century it was even used to mean a turkey-c**k  of two years or older.  Thus, a stag-night  or stag-dinner was a function attended by males only.

Similarly, in Middle English, hen could mean the female of any bird.  Thus a hen night or hen party is one which is exclusively female.

Answer 2

They're so-called just because of the fact that there was a way needed to specify that it's an all-men or all-women night.  

Answer 3

Hmmm... I don't know where you are from, but they are called bachelor/bachelorette parties in the US. Stag could just mean that the significant other is not there.