photo
Take a photo at the gate marking the Golden Triangle.
boat ride
Go on a boat ride across to a small island named Don Sao, belonging to Laos. No visa for Laos is required to make this trip. This is popular among tourists, and many small boats offer this service. The island is in Laos, and should you be so inclined you could claim to have visited the country, although you are not allowed to enter into the rest of Laos from there without a visa.