The first was when we were in the Grand Tetons in Colorado in late May - early June. Being those months we had thought that it was not going to be that cold so we didn't pack any of our winter clothes. Bad mistake. That night it probably got to about 20 degrees. My brothers and I each had about 3 sweatshirts on, a few pairs of pants, and like 10 pairs of socks, while the rest of our family was in the heated camper, ugh.
The second instance was actually on the same vacation but about to weeks later. Thankfully the weather had finally taken a turn for the better in terms of the temperature. However we did not take into account the precipitation. That night was the last night of our vacation and we were all ready to get home after three weeks of camping. That night we fell asleep, but at about 12 a.m. me and one of my brothers woke up and found it was pouring rain outside and there was about a 1/2 inch of water in our tent. We fell back asleep not thinking much of it, however at about 3 a.m. me and the same brother woke up again and found that there was probably 2 to 3 inches of water in our tent. All the while my other brother was still sleeping. We decided that we could not stay in the tent, floating about. So we decided to go into our camper whether my parents liked it or not.
Those were the two most memorable experiences in terms of camping that I can remember. I am sure that there are many more that I cannot recall. All in all it is great to go camping, however there is always something that goes wrong every time we go camping.