I dont know if you can consider this a trip because i have never tried anything more extreme than cannibus but that is the best way I can describe it... Anyways it was the middle of July (last summer, I was 22 at the time) and I was out camping with my wife and the inlaws. Two of my wifes siblings smoke (she does not approve) and on my way to relieve myself I saw of the two of them using a g-bong and went over to check it out. I had smoked before but had not until this point had enough to affect me very much at all. They gave me a large hit and after doing my business I went back to the fire to sit with my wife and some other family and grabbed another beer.
After a few minutes I started having muscle spasms and my body felt very warm which is pretty normal for me when I get fairly high. I started feeling a little paranoid and after a little bit I told my wife I was tired and headed towards the tent, I think she went down to the river to brush her teeth or something. My two dogs followed me to the tent. It was dark out at this point and I was starting to become afraid. I realized I did not have a flashlight with me and could not see into the tent, so I just sat outside on a large wooden box I use to store tarps and blankets for camping and watched my dogs.
This is where things started getting really messed up. The dogs seemed like they didn't know who I was and seemed to be acting aggressively towards me. They were both facing me and walking very quickly side to side in the tall grass kind of circling me in a quarter circle. Their heads stayed low and they appeared on the verge of attacking. The snores from my parent-inlaws tent across the large field/campsite echoed over to me and I could hear them as if I were just outside their tent. The that the dogs were making moving through the grass combined with the rythmic snoring started producing a techno-like music effect in my mind, with the snoring playing the base and the grass as kind of a chshh chshh sound being more continuous and not in rythmical beats like the snores. Crackles from the campfire, which was a long ways away, started coming into the song and my mind would replay a single sound (such as a crack from the fire) hundreds of times the exact same way i first heard it. I would hear all of these sounds on an exact beat in my techno. The kids started running around and chasing each other, fighting over a lit battery powered lantern. One of my neices was keeping it from the other one and I heard her yell "you cant have the light" which seemed to echo over and over again and turned into the chorus of my song. Everything seemed very dark and I was nervous. My wifes two siblings who I had smoked with earlier were now sitting by the fire and talking and laughing, but I mostly only heard the laughing and I believed they were laughing at me, they werent the kind of laughs that one enjoys hearing. No one but them was around the fire. So all of this seemed to take over an hour or two but Im sure now that it was around 15 to 20 minutes (maybe less who knows).
I finally caused myself to relax by getting into a meditative pose (I didnt really know what I was doing I sat a certain way and felt immediately better) The dogs were not agressive towards me and the techno stopped immediately. I saw my wife walking back up towards the fire and went to join her and brush my own teeth. I started getting nervous again because I was afraid she would find out that I had smoked and would be upset. Now, around the fire it seemed as if there were two sides, good and evil, my wife on the good side and her siblings on the evil side. They were still talking quitely and laughing loudly. I walked over to my truck to brush my teeth but before I could start I threw up (at least it wasnt after I finished) and just passed it off as though I had drank too much (even though three beers on their own could not make me puke). After I brushed we went to our tent and I pretended to read for a bit while she read and then fell asleep.
As an afterthought, although this was a really frightening experience for me I realized afterwards that I actually really enjoyed it. I look foreward to expirimenting with shrooms someday and other hallucinogens to see how the experiences compare to this one.