this super mutant had a rocket launcher and was on the roof of a building. He's obviously blowing my butt sky high... tried to throw a frag granade up to him and it hit a ledge at the last second and blew up in my face...
If it's Fallout 3 then you're just soft. If it's New Vegas, let Boone take care of 'em. Though I think I've eaten my own grenades in both games, so I'm not one to talk.