An interesting thing travelling to the pleasures of the Cambo border towns, but as luck would have it, you left your passport at home etc.
A fact is if you go to Khao Wihan Preah in Srisaket, when you leave Thailand, you get a little bus ticket to walk over to the temple that is in Cambodia. No Passport required.
Over there is all the dodgy booze and cigarettes you can dream of. Some good, some not so good.
You can also get a guided tour down to the road at the bottom of the mountain.