hmmm.. are you going to be somewhere where everyone brings the food/beer/etc. or at a resort with bars?
If a resort.. order lower carb beer or drink a mixed drink with low calorie/carb mixer. If eating in restaurants.. there should be low carb choices, or very close, you can choose.
If everyone bringing their own.. maybe you could buy some lower carb drinks and food to add to the pile?
That said.. one day is not going to end your low carb lifestyle unless you let it. It will probably throw you out of ketosis and you may or may not gain a few water pounds back, but once you go back to eating correctly it will be ok.
I would say the biggest danger.. from experience.. is continuing to eat high carb after you cheat, giving up.