With more than a little training and sound counseling you will survive the ultimate test of manhood - the stag night.
Lets start with alcohol consumption. Adjectives such as vast, copious and obscene would be used to best describe how much you will be expected to consume over the weekend. From the innocent pint of beer to the vomit-inducing cocktails, you will be drinking the lot.
How can you prepare for this in advance should be your question. Trips down to your local ale house, get friendly with the landlord and taste all he has to tempt you with, the aim to build up your tolerance levels.
Try to remember the old wives tale: a glass of milk will line your stomach and eating will act like a sponge to soak up the alcohol.

Obviously your so-called mates will be out to stitch you up at every available opportunity. Be on your guard, never let it slip and watch out for the married ones - they have revenge in mind!
If anyone is to be in for an unplanned swim, no prizes for guessing it'll be you - fully clothed. Pack wisely!
Finishing on the packing theme, don't forget your sense of humour. It is a must for any stag to be 'up for it' and if you have left your S.O.H. at home it will be an uphill struggle.

Good luck, black cats crossing your path and four leaf clovers ... maybe just maybe you can return home with both eyebrows intact, nursing a minimal hang-over having had a blast.