Stag party is referred to as bucks' party in Australia, bachelor party in South Africa and America, stag party in the UK. The word stag is associated with manliness. The correlation is relatively ancient when stags where supposed to be highly virulent in their abilities to woo the female counter part.
The tradition is observed even today, but has taken a more elaborate and extravagant form. Previously it used to be more of the 'night before the wedding' celebration, which was more apt in the sense for a stag night. These days, boys are very careful not to plan the party too close to the wedding. No bride would want her hubby to be in the state of half intoxication with a terrible headache and unable to pronounce the vows!
The traditions differ in various countries. In European countries like France, the French terminology for a stag party would translate to burial of the bachelorhood. Pretty dramatic, but it is also true.
The tradition seems to be more or less same throughout the globe. The day starts with a light get together and fun activities. The activities part sometimes is typical of the region. Mostly it would involve doing things a married can never do any time in his life. This would translate into adventure sports and dangerous but fun activities.
In Argentina, the groom to be is stripped of his clothes and driven naked in a car throughout the city for all the people to know that the guy is going to get hitched! Such pranks are common in other countries as well, where the groom to be is said to be tied to a pole naked.
It is said that in Switzerland, random squares are drawn on the grooms pants and he is taken to a bar, where the girls are asked to cut the patches using scissors!
Dressing up the guy in funny clothes that speaks out funny messages is another common custom. For extreme make over, the stag is dressed up as a female! When else can you see your best mate being dressed in 'man'kinis and G strings!
Stag night is usually blur for most. It involves extreme booze binge with bar crawls. This may or may not involve strippers.
The ultimate essence of stag do is to have a fun time at the groom's expense!