I haven't done too many stupid things, but one memorable one was going out for a night hike with my buddy and not taking a flashlight on the grounds that our 'night vision' would be sufficient. Didn't consider that on a moonless night under a heavy canopy, with a bunch of other kids running around shining their lights in our faces, our 'night vision' might be somewhat compromised. Me and my buddy spent a couple of hours tripping over rocks and roots on the trail.
With regard to the OP, Racerx, I can relate to that situation. Once in scouts we were on a wilderness bike ride without our leader, and by the time we got to our designated camping spot it was pouring rain and getting very dark. At the campsite were a number of very unsavoury characters with not much gear of their own, standing around in the rain drinking booze, swearing and yelling and throwing burning embers around the place. A couple of guys said not to worry about it, but our patrol leader (a kid about 15 or 16 years old) decided it wasn't safe to stay and that we'd keep riding to a different camping spot. We got to our new spot within about half an hour, and we were soaked but spent the night safely. In hindsight, that kid made a very wise decision in difficult circumstances, and I've been thankful to him for it ever since.
With regard to the OP, Racerx, I can relate to that situation. Once in scouts we were on a wilderness bike ride without our leader, and by the time we got to our designated camping spot it was pouring rain and getting very dark. At the campsite were a number of very unsavoury characters with not much gear of their own, standing around in the rain drinking booze, swearing and yelling and throwing burning embers around the place. A couple of guys said not to worry about it, but our patrol leader (a kid about 15 or 16 years old) decided it wasn't safe to stay and that we'd keep riding to a different camping spot. We got to our new spot within about half an hour, and we were soaked but spent the night safely. In hindsight, that kid made a very wise decision in difficult circumstances, and I've been thankful to him for it ever since.