Should the groom pay for his bachelor party?
The groom usually pays nothing for his bachelor party, although there's an exception to that rule should the bachelor party take place out of town. If the bachelor party involves expenses such as airfare and hotel, you do not have an obligation to pay the groom's way.
In a nutshell, the best man duties involve:
Planning and arranging the stag do.
Writing a brilliant best man's speech.
Assist with picking the suits.
Help the groom get ready for the ceremony.
Enter with the groom.
Look after the wedding rings.
Greet the wedding guests.
Dance with the maid of honour.