A guy in my father's platoon in Viet Nam killed himself like this. They had a little slit in the guard bunker that they would toss grenades out of during the night to light up the area and see if anyone was incoming. My father says the guy was always high and didn't get the grenade through the slit. The commanding officer told the guy's family that he died in combat.

EDIT - Since a lot of people are asking why they would use grenades to light up an area, my statement was incorrect. It was a story I heard from my father a long time ago, and I guess my brain twisted it. I asked him why exactly they tossed grenades and this is his response from an email he sent me - be easy on him - my father is a straight edge kind of guy - has never done any drugs and knows exactly how many times he has been drunk in his life (twice), so he will sound a little naive/ignorant about being on drugs

*"We randomly tossed out grenades while we were pulling guard duty at the bunkers at night. We did not do it frequently but just randomly. The grenades do not provide any light. They just explode. On really dark nights you couldn’t see much and we were isolated. We tossed grenades to put some fear in the VC. I have never understood why the VC didn’t sneak up to the bunker and throw in a grenade in. It would have been chaos. They were not as brave and bold as the films make out the VC to be. They were just people like all of us.

Guys on drugs tend to see stuff not there and are afraid. A guy from another squad was at our bunker one night. He was on duty and woke us up saying he saw movement in a hedge row 400-500 meters to the left of our bunker. We called in a Cobra gunship and it lit the area up with tracers and rockets. I never saw any movement. The next morning one of my squad came to me and told me “Sarge, he was just high on drugs.” If he was, it really fooled me.

What all of the guys in my squad thought happened was that this guy was sitting in the culvert halve on top of his bunker. We often did this when pulling guard duty. He then pulled the pin and dropped the grenade, dark of the moon, after 5 seconds it blew up. The other possibility is that he pulled the pin and released the handle and lost track of time. We told our suspicions to the 2nd Lt. but were instantly told it was a VC firing one grenade from an M79 into the culvert halve. The VC must have been the best shot ever and the only time while I was there that the VC ever fired at our bunkers. Makes no sense but it is better to list him as KIA rather than admitting he was high on drugs. The Lieutenant gave us a stern look and stated that it was undoubtedly an M79 round fired by VC!!!!"*