When picking YOUR name for a social media site do your best to be original. If someone is using the name you'd like to have you should smoke a joint, put on your thinking cap & come up with something unique, creative and sets you apart from the others. If there are 100's of users using that name, for an example I'll use StonerGirl. You won't step on any toes by adding some numbers or underscores to it because so many are using it. If you use a name that only one other person is using, they might get a lil' peeved. I know I would. If someone made up a twitter name like @greenthumbgirls420 I would not be flattered, I would probably feel annoyed. I hate when someone copies my ideas and I know others don't like or appreciate it either.
xx Samantha xx