Mine would be a backpacking trip up Copper Peak, here in Washington. It was me, my mom's boyfriend, his 2 kids, and my brother. The mountain is the 18th tallest and the climb up is a class 3-4 (meaning moderate-hard, there's a chance of dying if you mess up D:). Me and my bro had no experience in this sorta stuff. We had 3 days to summit, which was more than enough. Everything started out fine at first. The weather was perfect and there weren't that many bugs out. We climbed for the whole day and eventually reached the end of our scenery, which was replaced by the side of a smaller mountain that had a large amount of ice and rocks.
It looked like this:

Except this picture must be from some other side/time, because there was a cliff at the end of the ice, meaning if we fell/slipped, we would probably die. We survived that too, and reached the first lake. There's another one but it's not good for camping at. We found a good spot and setup our tent, made a fire, ate, and slept.
Now here's where it sucked. I was told that we were going to be in eastern Washington and that it would be around 70 degrees. And remembering my last backpacking trip, I figured I would pack a small blanket for the night. Well it turns out night time is cold, and it dipped below freezing. Everybody was fine, except for me. I was freezing my ass off. I don't think I got more than 20 minutes of sleep that night, because it felt like forever. Plus having to piss like 3 times sucked (however, one time while I was taking a piss I looked up and saw the stars. If you want to see the most beautiful sky ever, go into the mountains at night. It almost made the whole trip worth it).
Anyways, it gets morning and I make a fire before everyone is up. I'm exhausted and can barely form a coherent sentence, but I brought along a 5-hour-energy which did help some. Not going to bore you with details, but we basically climbed to the second lake (frozen) where us kids decided to stay while my mom's bf summited. I took a nap and woke up and decided to climb back down to camp with one other kid. The trip back felt like forever, and I couldn't even walk. It was more like a controlled-fall in which I just stumbled over everything. We were at the backside of the first lake and we had to walk a trail right on the edge of a cliff which drops straight into the water with some sharp boulders sticking out. I stumbled over something, and fell. Scariest moment of my life (lol). Luckily, my feet caught a tiny ledge in the rock that prevented me from falling any further.
So I survived that and we make it back to camp. Now there's another problem, mosquitoes. They were everywhere for some reason. I never noticed them before but I did now. They were also relentless. The tent was inhabbitable due to the heat, and everywhere we went they followed. Eventually I had the bright idea to cover ourselfs with mud. So that's what we did. We went down to an ice cold river and found a nice puddle of this weird mud/moss stuff which we proceeded to cover ourselves with. As it turns out, mosquitoes bite through mud. There were less, but they were still there. We basically endured them until nightfall when everybody else returned. The mud dried and we scratched it off. I had the one of the kids count how many bites I have, there were over 250.
It was time to sleep again. This time I wrapped my feet in old shirts and put on one of the other kids coats and I was able to sleep a little more, only this time I have the worst cramps ever. I think I had something like 4 feet cramps and 3 leg ones, all throughout the night. Which also resulted in me sitting up and freaking out. Needless to say I wasn't the most liked person there that night, and I also got sleepless night filled with pain.
We woke up, broke down camp, and hiked back to the car, where we proceeded to drive to the nearest town and ate some good burgers and fries.
So yeah, suckiest time of my life.