Being a big star has a lot of benefits, but there's also a downside ... like not being able to go out in public without being mobbed. 

Turns out, however, that one of the most famous women in country music has no trouble moving around in public and she says it's all thanks to her grumpy face. 

During a recent interview, Miranda Lambert revealed that she has no trouble hitting up local Nashville places like Walmart. 

“I kind of have this, what do you call it, R.B.F.,” she said, referencing the term resting b—- face. In other words, Lambert feels like people avoid her because she always has a serious look on her face.

Despite her serious face, Miranda says she doesn't try and look grumpy, it's just her natural look. 

“I don’t mean to, though,” she said. “I just do my thing and drink Miller Lite and hang out with my friends.”

Awww. We wouldn't be scared of you, Miranda ... well not too much anyway.