Back in the 70s I worked an office job for the Railway out of Vancouver BC. One of the switchmen on a switchcrew I was familiar with had served in Vietnam.
Really nice guy, soft-spoken, ready smile, just an all around pleasure to know. The guys he worked with, on the other hand, were assholes and treated him poorly.
They used to place track "bombs" on the tracks in order to scare the crap out of him. Track bombs are loud explosive charges designed to alert a switch crew to stay out of a track. They consist of a small package of explosive that is detonated when it is compressed by the weight of a railcar.
So his work mates would set these bombs up in order to scare the shit out of him. I walked into the changeroom one day and they were having a chuckle over scaring him.
I was pissed, and I said to them that if they do trigger PTSD in him that I hope he brings his service pistol to work and shoots the lot of them.
Apparently it hadn't occurred to them that fun and games might just have a serious outcome.
ALT Railway Fusee or "Track bomb"