Did the famous tubing in Vang Vieng, Lao. Actually, after the first day I ditched the tubes and focused on the non-stop party, the jars of vodka with coiled snakes inside and the death-defying swings across the river. Sadly the place is closed now after too many fatal accidents. I can see why, I still have a scar on my elbow as a souvenir but can't remember exactly how I got it.
One day and night at the desert in Petra, Jordan with just an old sleeping bag and, unfortunately, not enough water. Sleeping under the stars, going where it's not allowed and miraculously finding a bottle of water when I was seriously wondering if death from dehydration hurts a lot. But having one of the new 7 Wonders of the World completely for yourself: priceless.