The next thing you know it'll be a present for the alter boys, priest, chauffeur, waiters, waitresses, hotel manger/cleaners/janitor right down to the barman at the end of the night who won't sell you any more drink.
I hope I'm not too presumptuous but I don't think the majority of fellas would agree with a present for the groomsman, this seems to be more a tradition for the bridesmaids. I'd take the previous posters advice and buy them a few pints.
Do I get a present for posting??