Common places to find these nuisances can include radioactive barrels burried into the ground, or around dead wastelanders. This can be used to your advantage so you can loot the wastelanders afterwards.
If you're wearing thick clothes (and eye protection), then you can get close to these critters. Smack them as hard as you can, with the butt of your gun, or an effective melee weapon like a Baseball Bat. The most important thing is to not waste any ammo on them whatsoever. They just want you to, so they can dodge it and make you look like a total loser.