I have searched the web for things to do on the stag night, but there aren't so many (or my search was bad). So here are some items, which we put on the list (him = bachelor):
- mark him with some special clothes or accessory
- let him collect kisses from nice girls on a sheet of paper with their signatures
- let him collect reasons from people, why he should not marry
- let him mix a cocktail for you
- let him do a dance in a bar all alone on stage
- let him convince girls to do things for him (giving personal items, or pay for a drink)
All the tasks and some stupid rules were noted down so in the end he got a letter of acknowledgment from his friends.
And the important: Just care, that everybody has lots of fun.