Super mutant suiciders are one of easiest enemies to kill in FO:4. As far as gameplay goes they are a bit silly, but on a deeper level, they actually scare me a lot.
Think of them in as if it were real. Its grim. They carry a mini nuke in their hand and charge at you and then, well, you wouldn't survive. I'm actually saying this because I actually had a dream involving a mutant suicider. (I know. You know you've played too much when you start dreaming about it).
I wont bore you with crazy dream stories, but I had a 10mm pistol. As it felt real it was to close to just shoot the bomb I shot its legs and tried to hit its head, but it blocked it with its other hand, so I ran. It doesn't sound that scary, but that beeping sound following right behind you and the heavy thuds as it ran was terrifying.
I did manage to squeeze through a gap in the junk walls and escape, but yea. It was not a good feeling.
So yea. That's my little story for today.
Very well designed when something actually makes me un-nerved and afraid when I think about it in a real sense.