I have a 2 1/2yr. old daughter who loves to pull people's hair?

She's sweet as can be, but she has started pulling people's hair. People at church pick her up and immediately she grabs their hair, and gets this look of "excitement" on her face as she does it. Or we've even been in the Dr. office and she's climbed up in the chair beside a lady, reached over and grabbed her hair. She's got a very strong grip and you have to basically "peel" her fingers from their hair. I've tried telling her firmly "NO PULL HAIR" or "NOT NICE", I've swatted her bottom and her hand, but nothing seems to work. Does anyone have any ideas on how to break her of this? It's so embarassing when she does this. She doesn't pull my hair or her dad's, but will pull her 4yr. old brother's hair if he gets in her face to love on her.