So this happened in 2015 during the hungry ghost festival, so me and my group of friends (8 people) decided to skip school and went hiking, so as we were hiking up, we decided to try a different route from usual. As we were young and it was the hungry ghost festival, my friends dared me to shout during hiking, so i did. Then me and some of my friends shouted (cuss words) while hiking up lol, then while on the way up we decided to take a lot of selfies. Then after hiking down, we were going back to our own homes by our own bikes, so strange things began to happen. firstly, 1 of my friend straight got into an accident while going back, then i got into an accident a few days later and till this day i have the scar from the accident (the exhaust pipe burned my leg). Then we decided to look at the photos we took on the mountain and noticed that on 1 of the photos we taken, there was a white like thing like a head and like red ish mouth on the bushes behind us. We just deleted the photos and ignored it then a few days, around 4 of my friends started to get really sick, and they were really sick (fever+cough) and only recover after a few weeks. and those who did not shout had nothing happened to them. Till this day, me and couple of my friends have never went hiking since that incident. We never really talked about the incident since, maybe it was a coincidence and maybe not? nobody knows

tldr ; don't shout during hiking