Just in case you think you need to justify this (and you don't), suppose you're a shrewd, tough man who has bought and bloodily dismembered many software companies. So what. If a man doesn't relinquish his bachelorhood properly, he has embraced cowardice, and will be disgraced. When he's fifty, for example, he'll be at a college reunion, and the captain of the chess club, who became an appliance salesman, will get bigger laughs if anyone got arrested for throwing up in a fountain during his bachelor party.
As the Best Man you are responsible for a lifetime of memories. For the rest of his life every time your friend the groom stands by a fire with a beer in his hand and a buddy by his side-and the talk turns to the good old days, if he doesn't turn the conversation to his bachelor party and all the great things that happened, then you didn't do your job.
You must go to war against the average, you must fiercely battle the mundane. Your best friend has just asked you to step up to the plate, why you? Were you chosen by a formula so sober as dollar-cost-averaging? Has the groom taken stock of his dugout and decided that you were the safest bet? Or is it just because you are the biggest hitter he knows and he'd be a fool not to rely on you? Are you going to play it safe and bunt or are you going to swing the night away baby? To have a bachelor party "just like the last one" is tantamount to striking out. The whole team looses. Refuse to play for the loosing team.
If you do your job correctly, everyone who made it to "the Party" will tell all their buddies and in no time at all, it will be part of bachelor party lore.
"We few, we happy few, we band of brothers;
And if for no other reason, it's because you are the Best Man.